Dedication is showing up and doing the work as best you can.
Commitment is deciding to stick with the work (or the person, or the idea, etc.) even when the going gets tough.
There can be great dignity in dedication, but commitment says, This is bigger than me. This might even be bigger than us. I might not finish this work, but I’ll do my part.
Michelangelo’s artisans were no doubt dedicated craftspeople. But Michelangelo? The reason we’ve all heard of him is because he made a commitment.