Norelgestromin and ethinyl estradiol. These are really similar to progesterone and estrogen and just like the hormones you get in the combined pill. They stop you from ovulating, make your uterine lining thinner, and make cervical fluid thicker so sperm can’t swim through.
These hormones enter the body through the skin when you use the patch. With the pill, they go into your bloodstream after you’ve swallowed it.