Racism is when the group of people in power discriminates other groups of people due to race. In America (and most other parts of the world) white people have set up a system of white supremacy that puts everyone who is not white at a disadvantage. This disadvantage oppresses non-white people on a high, almost global, level. White people have the capability to be racist because their discrimination has the power to oppress.
Discrimination is treating someone differently because they fit into a certain group (see: xenophobia). When there is no power to oppress involved, there is no racism. It’s simply discrimination. If a Black person who owns a company doesn’t hire a white person, that can be considered discrimination based on the circumstances. That Black person, however, does not hold the power to systematically oppress the white person they didn’t hire. Therefore, that Black person is not racist, they are discriminatory.
Are these perfect definitions? No. They don’t go into how a lot of discrimination is based in racism. These are very good starting points though. Am I saying that discrimination is okay while racism is not? No. I don’t think most people would say that. What I am saying is it is important that we recognize the difference between discrimination and racism if we are to combat them both.