What racial differences did Lincoln perceive?

Abraham Lincoln is often called “The Great Emancipator” and hailed as a heroic opponent of slavery. However, just because he played a pivotal role in ending slavery in the United States doesn’t mean that he believed all races to be inherently equal.
When he ran for Senate against Stephen Douglas in 1958, Lincoln stated clearly in the debates that while he thought African American people should be entitled to live as freely as whites, he did not accept them as intellectual or moral equals. He didn’t want to give them the right to vote or hold office, and he was against intermarriage. He definitely thought that the white people should still be in charge of everything.

“There must be the position of superior and inferior, and I, as much as any other man, am in favor of having the superior position assigned to the white race. I say upon this occasion I do not perceive that because the white man is to have the superior position the negro should be denied everything.”—Abraham Lincoln, in the Lincoln-Douglas Debates

As racist as that opinion sounds to us today, Lincoln's view that African Americans should at least be able to live freely was a revolutionary (and unpopular) idea for the time. Lincoln lost the Senate race but won the presidency in 1860. A few months later, the Southern states (whose economy depended on slavery) seceded, and the Civil War began.
https://www.minnpost.com/eric-black-ink/2013/05/facing-facts-about-lincoln-and-his-views-slavery/