This is one of the most difficult plants to tell apart from poison ivy because they are both vines with leaves of three. In this photo they are growing intermixed, which they often do.
The leaves of the hog peanut have no notches, but poison ivy leaves sometimes have no notches.
Hog peanut leaves are never shiny… but sometimes poison ivy leaves are also not shiny.
The stems of hog peanut are very thin and delicate, like little hairs. Whereas poison ivy stems are thicker and in winter the woody poison ivy vines are still there, but the hog peanut. vine entirely rots away after the fall.
Below is a clean version of the image. Is it obvious which is which to you?
You can click either image to see them larger.