Legionary soldiers
* Were Roman citizens
* Served in the legions, which were the main units of the Roman army
* Were typically better trained and equipped than Auxiliary soldiers
* Received higher pay than Auxiliary soldiers
Auxiliary soldiers
* Were not Roman citizens, but were drawn from conquered territories and allied states
* Served in auxiliary units, which were smaller and less well-equipped than the legions
* Were typically less trained and experienced than legionary soldiers
* Received lower pay than legionary soldiers
Auxiliary soldiers played a vital role in the Roman army, providing additional manpower and specialist skills. They were often used as scouts, skirmishers, and garrison troops. In some cases, Auxiliary soldiers were even promoted to command legions.
The distinction between legionary and Auxiliary soldiers was eventually abolished in the late 3rd century AD, when all soldiers in the Roman army became Roman citizens.