Yes and no. I don't mean Greenskins need to wear uniforms, but they do still be unified in terms of Visuals. Right now if you compare the new squig riders with the old grots on spiders there's some jarring difference despite them being very similar units.
The squigs are bouncy, active, chaotic and out of control. Their riders wield crude weapons and they all wear a tattered robe looking kind of like insane lil monks. They don't look in control of their mounts in the slightest, they barely look like they're in control of themselfs and basicly ooze madness.
In contrast the ones on spiders are fairly static, sitting almost as if they're on guard waiting for something. Their riders wear tribal-like clothing with a lot of feathers. The madness is nearly completly gone here. They just look like random evil forest-creatures that want to eat you.
The difference in clothing and especially the lack of madness in the spider models makes them feel very disjunct. I think that could be done be improved with new models.