The Galactic Empire under Palpatine and into the time of the post-Palpatine Imperial Remnant had two types of rank-and-file foot soldiers: stormtroopers and judicial troopers.
Stormtroopers were composed of two types: the standard stormtroopers of the Imperial Army's Stormtrooper Corps, and Compforce stormtroopers, who were members of the Commission to Preserve the New Order (COMPNOR). Most Imperial Army stormtroopers were clone troopers like the clones of the Galactic Republic's Grand Army of the Republic during the Clone Wars, but an increasing number of the Stormtrooper Corps was made up of volunteers from the ranks of the Compforce stormtroopers and even the judicial troopers. Both Imperial Army/Stormtrooper Corps soldiers and Compforce troopers wore the standard white stormtrooper armor.
Judicial troopers were sometimes erroneously called Imperial Navy troopers, although they most often served aboard Imperial Navy warships. They wore black uniforms and helmets, and were descended from the Judicial Forces of the Republic Judicial Department.