I bought a succulent this summer. I don't know what it is but I treated it like a jade plant. It was doing great at first (see first image) but then it started losing leaves. I thought maybe it needed a bigger pot but that didn't help (see second image).

Can you help me know what it is and what I should be doing differently?

I don't even know where to start.

It might be a Kalanchoe but I really don't know. It looks like a case of not enough light and too much water.

Find some potting soil especially formulated for cactus, a smaller pot and a brighter spot for it to live in.

Good luck!

Looks like a very light deprived Kalanchoe. These need as much light as you can give them when grown indoors. Keep dry in fast draining soil.