The difference is that his financial backers and employers are holding them to account because of the threat of boycott. Their financial interests are at stake. Unfortunately, the general public is willing to look past the admissions of sexual assault perpetrated by Donald Trump against women who are in a business relationship with him. The power imbalance is huge and obvious. Had those same assaults been committed by a stage hand, that individual would have been reported and charged because that person has no real power. The Donald on the other has all the power... 
Society is the problem. It only took one man to call out and ruin Kevin Spacey's career. Where it takes many women to make an accusation and to take down a predator like Weinstein because "women are not believable".  The best example is Jian Gomeshi....