Question about Theodosius Obelisk Base

[Urselius]

I would not build up a universal idea about the dress of the Goths from this drawing. It is impossible to judge to what extent the artist was interpreting the weathered remains. For example the 'captured spoils' on the lower panel include a definite labarum (towards the left hand side), which would be a very odd thing for a Roman army to take from a non-Roman enemy.

If he kneeling group from the photograph are all Goths, then why are the group on the left differentiated by their dress from the group on the right?