I've been gardening for 19 years and I had to Google that exact question. I had big plans to spell it all out for you, in a language that was easy to understand. Hahahahahahaha Not so much. Basically, I read a bunch of articles that didn't give a clear answer. I think the answer is, no one knows the answer. Ha.
I came up with something along the lines of, all sedum are succulents, but not all succulents are sedum. Or vice versa. Your guess is as good as mine.
For whatever reason, I've always had this little thing stuck in my head: Succulents suck. Meaning, suck water. Their leaves are puffy and store moisture. When they're dry, you can tell by their sad, shriveled, deflated leaves. So what about sedum? Don't they do the same? I think of them as smaller, with more leaves, and more inclined to spread.
Then you throw a plant like Kalanchoe in the mix, to confuse you even more.
(I'm goin' with succulent.)
I'm sure someone will comment and answer the burning question for you all. The whole point behind all my "research", was so that I could properly identify the plant in these photos.
Enough with my very non-educational post. Here's a cute, tiny plant, growing in the pot with my little Maple tree, that I felt compelled to take a ton of pictures of.
(I'm goin' sedum on this one.)
I do know one thing for certain, this is a bell. ;o)