Abiraterone (Zytiga) is a first-generation ARSI. You usually have to take it with a steroid, which brings its own side-effects.

Enzalutamide (Xtandi) is one of the second-generation ARSIs (together with Darolutamide and Apalutamide, the so-called "-lutamides"). They sometimes have lower side-effects and are far more effective, including significantly longer overall survival, but obviously, everyone's medical situation is different and they may or may not be suitable for you.

So Abiraterone and Enzalutamide do play the same role (trying to prevent cancer cells from receiving testosterone signals), but they're not interchangeable. They're like a v.1 and v.2.