The medium tank M4 was based on the medium tank M3, and the Sherman shared many components with the Lee. The M4 utilized the M3's suspension, lower hull, and power train.

Known to the British as Sherman II, the M4A1's cast upper hull gave it distinctive rounded edges. This makes it the easiest of Sherman tanks to identify. Other identifying features of M4A1, which it shares with M4, are the rear of the tank and engine access panels. There are twin engine access doors in the rear hull and air cleaners at the top corners of these doors. M4A1 had twin square muffler tailpipes at the top of the rear hull above the air cleaners, a steel-covered air intake behind the turret, and solid engine access doors in the rear deck behind the turret.

Early Shermans--cast and welded hull--were built with twin fixed .30cal M1919A4 machine guns in the hull which were operated by the driver. These could be locked at any elevation between +8° and -6°. The driver's machine guns were eliminated on March 6, 1942. Also seen on early tanks were spoked idler and road wheels, three-piece differential and final drive housing, two fuel shutoff valves on the rear deck, removable headlights, vision slots for the drivers in the glacis plate, and the siren was placed on the left front fender or under a bracket just offset to the left of the glacis centerline. On tanks with dry ammunition stowage, one-inch thick applique armor was welded over the sponson ammunition racks and to the turret on the right of the gun mount where interior armor had been ground away to make room for the gunner's controls. Heavy-duty suspension bogies, with the return roller on the rear of the bogie instead of on top like earlier bogies, were introduced by summer 1942. The new bogies had 8" (20cm) diameter springs, 1" (2.5cm) larger than the springs of the earlier type. Originally, there was only one turret hatch (the commander's) in the 75mm gun turret, but a small oval hatch was introduced for the loader in December 1943. Retrofit kits were developed for tanks built before the loader's hatch was designed. A cupola for the tank commander later replaced his circular split hatch. The main gun in the first M4A1s built was the 75mm M2, which was shorter than the M3 and needed double counterweights on the end of the barrel to be compatible with the tank's gyrostabilizer.

The M4A2, the first welded-hull Sherman to enter service, was Sherman III in the British nomenclature style. The M4A2 used the same engine as the medium tanks M3A3 and M3A5.

Early Sherman tanks used the M34 gun mount. M34A1 differed from M34 by using a direct telescope as the primary sight instead of the periscope of the M34. The periscope was retained as backup, however. The M34A1 incorporated a new rotor shield, which now protected the telescopic sight on the right of the 75mm gun and the .30cal M1919A4 machine gun to the left of the main gun. Mount M34 had used a separate shield for the coaxial machine gun.

Identification points of later production Shermans are solid disc idlers and road wheels, lack of fuel shutoff valves on the rear deck, fixed headlights, periscope guards, sandshields, a travel lock for the 75mm gun, drivers' vision slots replaced by a second set of periscopes, and mounting of the siren next to the left headlight with a guard similar to the headlight clusters. Late welded-hull tanks had the 56° glacis replaced by a single-piece plate inclined at 47° from vertical. The 56° plate featured protruding drivers' hoods (or direct vision slots on earlier tanks) and was composed of several pieces welded together, which complicated production. The 47° plate was a single piece and eliminated the drivers' hoods. Larger drivers' hatches were also introduced with the 47° plate. Late tanks also were built with a single-piece differential and final drive housing.

The engine compartment of the M4A2 had a single-piece rear armor plate that extended below the sponson level. Two rows of bolts converged to make a "T" shape in the rear armor plate, and an exhaust deflector was mounted below the plate, with twin exhaust pipes converging in the middle of the tank beneath the deflector. The engine access grill doors on the rear deck were approximately as wide as the turret bustle.

M4A3 would be Sherman IV to the British.

All M4A3s were fitted with the heavy-duty suspension bogies and single-piece final drive and differential housing. The rear armor of the M4A3 reached below the sponson line, as on M4A2, but M4A3's rear deck engine grill doors ran from sponson to sponson. M4A3 also lacked the row of bolts that were embedded into M4A2's rear plate. The 56° glacis on the early tanks was made up of less pieces than M4A2's, and the weld line was consequently shorter.

M4A4 was known as Sherman V to the British.

M4A4 had a longer hull than other Shermans due to its large Chrysler multibank engine, which was five automobile engines combined in a star shape geared to run as a single engine. The A57 was also installed in the medium tank M3A4. The bogies were distinctive on M4A4 as they were spaced farther apart than other Shermans. The centers of M4A4's bogies were 63.625" (162cm) apart, while those of other Shermans were 57" (145cm) apart. There was a rectangular, square-cornered bulge on the rear deck of M4A4 that covered the engine's radiator. The radiator filler cap was in the middle of this bulge, and a thin air inlet grille was between the turret and the radiator bulge. There was also a blister in the floor of the M4A4 to allow the engine cooling fan to fit into the rear compartment. The glacis of M4A4 was simplified from that of M4A2, with five plates welded together rather than the M4A2's seven. All M4A4s were produced with the three-piece final drive and differential housing.

M4A6 used the extended M4A4 hull with some modifications for the different engine. The radiator blister on the rear deck was round-cornered and lacked a radiator filler cap, which differentiates it from M4A4. There was also a bulge in the engine compartment floor to give the engine sufficient clearance. The M4A6 had a cast front upper hull similar to that of late model M4 tanks which were also built at Chrysler's Detroit Tank Arsenal. All M4A6s used the single-piece sharp-nosed final drive and differential housing, as well as large drivers' hatches and a travel lock for the 75mm gun. The hull ammunition racks had the usual applique armor welded overtop of them, but the turrets used in the M4A6 were of a later design and did not need reinforcing armor.

The RD-1820 was a supercharged single-row radial engine capable of using fuels ranging from diesel to low-octane gasoline. Its governed speed under full load was 2000 rpm, and it weighed 3900lbs (1800kg) without its air cleaners and fuel and oil filters.

The designation of medium tank M4A5 was given to Canada's cruiser tank Ram II.

The British nomenclature for 76mm gun Shermans involved adding an "A" to the designation, so M4A1(76)W became Sherman IIA.

Wet ammunition stowage was incorporated into the M4A1(76)W, hence the "W" suffix in the designation. This involved storing the ammunition in double-walled boxes. The space between the walls of the boxes were filled with water; ethylene glycol to prevent freezing; and Ammudamp, a rust inhibitor. When these boxes were penetrated, the water would snuff out the resulting ammunition fire. Wet ammunition stowage, and the stowage of most of the ammunition under the turret rather than in the sponsons, drastically reduced the Sherman's propencity to burn; the "W" tanks were no longer "Ronsons." In 76mm gun tanks there was a 6-round ready rack in the turret surrounded by 2.1 gallons (7.9L) of water and a box on either side of the drive shaft, one holding 30 rounds and the other 35, with a total of 34.5 gallons (131L) of water. The welded applique armor was eliminated in wet stowage tanks, as well as most of the turret basket to enable use of the floor ammunition boxes. A partial floor was retained which was suspended from the turret ring.

Seventy-six-millimeter gun tanks used a new turret modified from the medium tank T23. The T23 was never standardized, but that test series went on to produce improvements that were incorporated into other tanks (like the T23's turret), and ultimately culminated in the M26 Pershing. The turret of the first M4A1(76)Ws were fitted with a split hatch for the loader, which was replaced with the small oval hatch about one-third of the way through the production run.

The 76mm guns themselves differ in the following ways: the outside recoil surface of the M1A1 was lengthened by one foot over the M1, thereby allowing the trunnions to be moved forward and providing better gun balance; the M1A1C had the end of the barrel threaded for a muzzle brake; the rifling of the M1A2 was one turn in 32 calibers versus one turn in forty for the other weapons. All M1A2s were equipped with muzzle brakes.