Well, we've only really seen two specific Garlean legions so far in both 1.0 and ARR (the VIIth, led by Nael van Darnus, and the XIVth, led by Gaius van Baelsar), and troops for both seem to follow the will of their commanding Legatus (especially in the case of the VIIth, who even with Nael being 'killed' still zealously threw themselves into battle against the Alliance at Carteneau without a commander, simply acting according to his general will that is, 'cleanse' the 'savage lands of Eorzea from it's taint').

Of course the VIIth was virtually completely annihilated in the Calamity, with any survivors presumably absorbed into the XIVth so it's possible any specific differences they had would have been lost in the adoption of their new posting.

I remember it mentioned somewhere in the old 1.0 forum (now archived) that there is in fact fourteen separate Garlean legions incidentally, or rather, was given the now loss of both the VIIth and XIVth in Eorzea.