The difference is that we're trying to do something about it. Kids learn about many of the bad things America did (slavery, extermination of the native Americans, Vietnam war atrocities, nuking Hiroshima and Nagasaki, etc.). They're taking down civil war monuments all over the country. The same will happen with Columbus soon--Los Angeles has already renamed Columbus Day in favor of the indigenous people he exterminated, and there are proposals to do the same/take down Columbus monuments in Baltimore, D.C., New York, etc.