well one is steel and the other aluminum.. i'd imagine that's one of the biggest differences..

also, based on specs from business cycles and harris cyclery, the concept's trail is about 66.6 mm v. the bareknuckle's 52.7 mm (figured with 23mm tires)

you can probably get them to fit the same but they probably will feel a bit different
i guess that's part of the point in having different bikes...