(DA and the 30 character title rule. Bleh!)
Four years and I'm just now hitting 90 deviations? Kind of sad...

Here's another "There's a Difference" pic. I did this one to point out the pysical (mind went blank and I forgot how to spell it...) differences between the Yaashiin twins before I did their profiles so no one is all "you posted this person twice!" Before I delve into the "how to figure out which one is which from a glance," I just wanted to say no, they don't dress differently. They like dressing alike, don't ask me why. I only put them in different outfits than each other so you could identify them immedietely.

Takuya: His hair sways to the right side (well, his right side). If you see him from his profile (side view) and you can't figure out which way his hair sways, he'll always be on the left (that's if his back is to you. If he's facing you, he's on your left OR right, so be careful!) His collar has green on the top. When he looks at a person, he looks AT them. He's most likely the smiling one. Posture wise, he's more relaxed and comfortable.
Toya: Toya's hair sways to his left side. If you see him from the back, he'll always be on the right side, but if you see him from the front, he could be on either side of Takuya. He wears glasses (he reminds me of megane characters like Kyoya and Uryu) but you'll rarely see him with them on since he wears contacts most of the time. His collar has yellow on the top. He's rarely smiling for no reason at all (seeing a person he knows is no reason at all). When he stares at a person, he looks THROUGH them. Posture wise, he stands straight up--like completely straight, and he does not look welcoming.

Hope that helps. I also ALWAYS seem to draw Takuya first, so if you can ever figure out which one I draw first, not only are you good, but that'd help. For this pic, I tried coloring their hair dark brown first then layering over it in black. It looks better now actually. And I colored the background in light green becuase the whiteness was killing me! Also, there used to be a picture of something else there that I just couldn't finished and I didn't want what I erased to be visible.
I don't know though, but Richard may have made what's on the next page of my sketchbook slightly visible in the background. I can't tell. If you care, it was the Cliche Cast line-up.

Takuya and Toya Yaashiin belong to me.