Both "Daddy's Boys" - They were both groomed by their fathers to take over the family business. In the case of trUMp, it was literally, the family business. For Harbaugh, it was the family profession. They were expected to be like their Daddy was, and they have followed through on that.
Both like to mouth off - Neither the chUMp nor the trUMp can avoid jaw-jacking opportunities, especially if the lip-flapping picks on others. You will not hear these guys waxing philosophically on the issues facing Americans, or spiritual questions, or solutions to vexing questions. These dudes like to pick on others, plain and simple. If it's not Muslims, it's Referees.
Both see themselves as the center of the known universe - The Orange chUMp thinks that no rules apply to him, no matter how many of his predecessors had to follow them. The Blue chUMp thinks that no rules apply to him or his school, no matter how many other coaches and schools have had to follow them.
Both enjoy socializing with teenage girls - Harbaugh likes to send notes to high school girls, ostensibly as a recruiting tool. Trump likes to rape teenage girls, just because he can.
Both are very good at what they do - Harbaugh is a great football coach. Trump is a fantastically gifted LIAR.