Although the two terms are often used interchangeably, they are two different types of structures. A cabana is an outdoor structure with three sides and a roof. The pool cabana design provides poolside shelter and usually includes a private changing room.
A pool house is a separate guest house built near a backyard pool. It requires building permits and full utilities like any other house. A pool house plan often includes a small kitchen, bathroom, living space, and perhaps a guest bedroom.