Couple things i know for sure without knowing year and model.
Finding cheap moto rims and tires is a challenge in itself. So estimate to pay close to aftermarket price on a set of those.
If you buy the SMC you already have them.
The enduro model will have "better suited dirt adventure front forks".Better rebound tuning.More travel for hard terrain etc, little things that make it a pig or something cool.you get the idea.
There could be other things , i read somehwere the SMC-R had 12.5 to 1 compression and same year enduro had 11.7 to 1. Cant confirm that.
current -2007 690SM