One big difference? Clinton is viewed mostly positively by nonwhite registered voters, and white women consistently view her less negatively than do white men. Trump, on the other hand, is consistently viewed strongly negatively by nonwhite voters and often about equally negatively among white women. (More than half of white women view both negatively.)
Over time, those patterns haven't changed much. At the outset of the campaign, Trump saw a quick surge in favorability among white voters that wasn't matched among nonwhites. During the early part of the campaign, though, Clinton's numbers among white men sank and never recovered. Nearly three quarters of registered white men view her unfavorably — a figure nearly matched by the opinions of Trump among nonwhite voters.
A large part of Trump's challenge with nonwhite voters is the strong support Clinton gets from African Americans. Black voters are consistently more likely to view Trump strongly unfavorably and less likely to view Clinton the same way. (The sample sizes here are small, yielding a lot of volatility, but the pattern is pretty clear.) Less than a quarter of nonwhite voters see Clinton in a strongly unfavorable light while slightly more than half of whites do the same, led by white men.
White men have been the core of Trump's support over the course of the campaign, a fact that correlates to these favorability ratings. These are the fault lines within the electorate: White men back Trump, nonwhite voters back Clinton and white women are the rope in the tug-of-war. It's worth bearing in mind when you hear mention of the two least-popular candidates in modern history that the same fault lines come into play there, too.