Great advice Bev.
I would like to add, when you redo your soil and fill the containers fill them almost to the top of the pot. Then after replanting add a top dressing of small gravel/pea gravel or chicken grit. This will keep the leaves up off of the soil.
If the two plants are the same cultivar, 'Red Heart', it could be that one is getting more sun? The smaller one is looking like it it me etiolated? Can you show us a photo from the top of the both plants?
The soil from what I can see looks to be a bit wet. The latest information on growing in containers are saying not to put rocks/gravel in the bottom of the containers. Just mix in pumice/grit/ or larger sized coarse sand with your potting mix.
Also, usually the older an rosette is the larger it will be if given room to grow.
It also looks like your weather is just beginning to warm up, this can be why they aren't producing offsets yet.
