Madtripper,
I assume if it was a tree peony it would say tree peony. In herbaceous peonies there is a flower form which is called Japanese. Although Japanese and single form is similar they are not the same. A single peony has stamen and anthers. A Japanese flowering peony has stamen which are transformed into a slightly broader structure and these structures generally do not have pollen.
A Japanese tree peony would have a woody stem up above the soil level. It would also be a grafted plant. The root of a grafted plant would be enlarged.

Without having ever seen the peony I can say that if it is a tree peony you will know in the fall when the frost comes. A Herb peony's stems will wilt and buckel with the frost and freeze, but a tree peony will not. You will have a rigid bare leafless tree after frost just like any other tree if it is a tree peony. In the spring the frame will leaf out just like any other tree, and a herb peony s will come up from shoots. You will know in the fall or spring.
Have a good summer.