It’s sort of two different things.
Blood type and Rh factor both do have to do with antigens/proteins in the blood.
Blood type is inherited from your parents and you have either A, O, AB, or B. Everyone fits into one of these four.
Rh factor is another defining characteristic of the blood, also having to do with inheritance, and you can be either Rh positive or Rh negative. If you are negative you don’t have the Rh protein.
So, you can be A positive or A negative, B positive or B negative, AB positive or AB negative, or O positive or O negative.
O negative is the universal donor not having any proteins that can harm someone with other blood types. If you introduce a protein that the recipient doesn’t have, that’s when you get a problem, and why blood type is so important.
Do you need it defined more than that?