@literally45-- I think the effects and side effects of both are related to the specific product. Not all supplements are the same. Some are more potent, and they can be made from different parts of the plant.
From my experience, maca seems to be better for general health and strength and tribulus for sexual desire.
Maca's side effects are almost nonexistent but tribulus usually causes problems. It might be high blood pressure, prostate problems or hormonal changes.