Is there any differences between poison oak and ivy?

Different yet same: The plants are different. Poison oak grows like a bush or a small shrub and poison ivy grows as a vine along the ground or up tree trunks. The reactions that people develop to these are the same. The sap of any of the plants in the rhus genus (poison ivy, oak and sumac are common but also mango, cashew and pistacchio) may cause a rash that can itch and blister 12-48 hours after contact.