Poison oak and poison ivy the same thing?

Different plants: Same clinical presentation of contact dermatitis. Treatment is the same. However, these are two different plants.

Yes: Poison ivy (in eastern us), oak (in western us), sumac (in eastern us) are 3 species in the genus toxicodendron or rhus which all produce urushiol oil, the substance that in sensitive individuals produces contact dermatitis. Urushiol is very stable and can be blown on leaf particles into contact with the skin or carried on clothing for over a year so dermatitis can occur without plant contact.

Different /same pbm: Poison Ivy has a compound leaf with 3 sharpened arrowhead like blades. Poison oak has a similar compound leaf with 3 blades that have rounded edges, like a post oak. Their existence in some regions overlap in some areas. They both produce the same oil which produces a skin rash within 24 hrs of contact.