Ingram was more coordinated and fluid which is why he played so many spots. Chad and Quentin are DL only.
When you watch the clips back-to-back, their movements are similar. A little tight, not as smooth as an Ingram, but forceful and explosive.
Melvin Ingram was more versatile in high school. He was a RB, kicker, LB, etc.
Chad and Quentin are used in very similar ways. Inside, outside. The first few plays of their respective senior HLs are almost identical.
I can't take credit for this (I stole it from @brock) but it's perfect. Quentin Williams is very similar to Chad Thomas. Neither guy was a smooth, polished pass rusher but they produced based on athleticism and motor. Both guys played inside and outside and both starred at quality programs. Look...