How would an ancient army fighting a similarly equipped army differentiate themselves in the era of equipment difformity?

by MithraDateX

Uniformity was uncommon in ancient antiquity, and for clarification, how would a Hellenistic army differentiate themselves from another Hellenistic army? Shield monograms and insignias? Perhaps similar color schemes? And what about tribal warbands? How would a Celt differentiate from another Celt?

Edit: Changed "common" to "uncommon".

ultramatt1

Hi, you might find these past responses to this question helpful:

Link 1 from u/prufrock451

Link 2 from u/waritter