Race is related to ethnicity but also relates to a lot of cultural factors. Race is also tied to people's perception of a person, and also tied to an individual's identity. There are more and different races than ethnicities.

Additionally, race is linked to discrimination. Two people can be the same ethnicity but different races, because their culture and ancestral nationality are different. This often leads to people of a certain race being seen as lesser than, even though there is no biological difference. I.e. the Irish, and Italians, who are considered white now but weren't in the past.

On top of that, people of different ethnicities can be lumped into a singular race and be discriminated against. Like Hispanic people, who have native American, Spanish, and many other ethnicities mixed in. Or Asians who have probably the most varied amount of ethnicities in their singular "race."

Conversely you can have someone who is mixed and is technically mostly genetically ethnicities that are considered white, and would be white passing, but because they are known to have a black parent or grew up in the black community, they are considered to be a person if color, and are discriminated against in the same way as someone who is more ethnically a POC.

This discrimination and racism can cause generational trauma and wealth disparity. Which is important to learn about so people can understand how systems, at least in the U.S., are literally built in a way that makes traditionally discriminated against races more likely to be born into poverty and less likely to get out of it. CRT strives to educate the our population on these issues.

CRT teaches about the fact that Black people and other POC in the United States have been discriminated against for generations, this discrimination is/was codified in law and local ordinances. Like laws limiting POC from getting certain loans, or moving into certain neighborhoods. Then building roads around those neighborhoods separating them from the rest of the town, making it harder for those individuals to get resources. Or the fact that, in the U.S.,public schools are funded by housing taxes in an area rather than by equal funding. Meaning that low income areas (usually populated by minorities because of the previously mentioned reasons) will inherently have less funding.

All this leads to the fact that even though a lot of the racist legislation in the U.S. is gone, a lot of minorities in the U.S. have been lower income for generations. Meaning a lot of them are starting from less and will have less opportunity to achieve because the just don't have the same resources and education available. And today, because of all this, we are seeing things like schools being more segregated than ever, even more than they were even in times where segregation was in law.

If our population is not educated on these topics, these things will never change. These people will never get the help they need. This is why CRT in a lot of experts opinions is sorely needed in the American education curriculum.