From what I've seen, Limar is more of a hard-charging back who can also make a good hard cut right as he's about to be hit. Looking at his style of play, he's quite strong, and with another 15 pounds of muscle could easily become powerful runner with very good speed.
Irvin is more of an all-purpose back. He's pretty polished when it comes to the passing game, both as a blocker and a receiver.