I agree that Darwinism is natural selection, but social Darwinism is humans choose who is the most fit. This is what makes them different.

I agree that it is influenced by the environment and eugenics was stated because it was influenced by Darwin's theory as well.

I agree, he didn't like the way they treated the slaved people. despite all the bad treatment, they used their blood in their experiments and the slaves weren't aware of that.

In Europe and America, many poor, Black people were slaves. They treated the Black people very bad and used their bloods in their experiments without their constant. Darwin was influenced by what was happening in Europe and America, so he tried to figure out how did these people got their color and he refused the idea that says the people who are not the same color as we are and don't speak our language, should die.

Social Darwinism is a belief, popular in the late Victorian era in England, America, and elsewhere, where states that the strongest or fittest should survive and flourish in society. Darwinism and social Darwinism wanted the strong people live and produce and get rid of the weak people, so this how they are similar. Social Darwinism was the applicant of Charles Darwinism scientific theories of evolution and natural selection to contemporary social development.

Eugenics is the theory that humans can influence our own evolution, though selective breeding, or genetic enhancement. I agree that Darwin's concepts contributed to eugenics because Eugenics was coined in 1883 by the British explorer and natural scientist, France Galton, who, influenced by Charles Darwin's theory of natural selective.