Different bike

Big change in how you ride it. The XR is very mellow and can be lugged around. Soft suspension makes roots and things easy but jumps harsh (and I don't recommend a lot of jumps even though I jumped my DRZ250 more than I should have).

The CR125 will need to be revved and good clutch work to get the most out of it. Suspension will be harsh in the woods and stiff on the track but will absorb hits better.

Jetting will have more of an impact on the performance of the CR125 as well.