>>7977162The in universe explanation is that by the time ANH starts, Stormtroopers are not 100% clones. This explain the difference in heights and helmets between the troopers, although it made Leia's remark about "aren't you a little short for a stormtrooper" doesn't make sense, unless the Empire actively discriminates against manlets to join their combat ranks. This explain the helmets because some people need bigger visor to see through than others.
