I'm probably totally wrong, but my guess would be what I call a "florist's azalea." I don't know that that is a "proper" designation, but I have azaleas which I received as potted plants. I eventually planted them in my yard. They stay quite small without being pruned, never growing more than 2 feet tall, and the leaves are small, as well.
In comparison, I have azaleas that would grow to 10 or 12 feet tall, if I didn't keep them pruned to 6 or 7 feet. The leaves on these plants are about 4 to 6 times larger than on the florists azaleas.
I don't know what the difference is between the plants, other than the size.