Similar, but not the same. Both can power run block, RI is better than KU in a zone blocking scheme, in getting to the second level and generally operating in space. KU is probably a better pass blocker. And yes, Richie is certifiably insane whereas KU is a wholesome Wisconsin farmboy.
If Martin is close to the same player he was two years ago, he is immediately the best pass catching tight end on the roster (including Nelson). Not a very good blocker and cannot play special teams. Chan may be looking for another weapon here and a proven commodity. Really all depends on whether his knee is 100%. If it is he will stick and is good to go for the year.