Why are PE Funds much larger than Hedge Funds?

In terms of AUM, PE Funds tend to be larger than HF funds given the same number of FO investment professionals. I hear that PE is much more scale-able (though I always thought public equities would be more scale-able). Why is that so? Also, if the same # of employees can manage a much larger fund in PE than in HF, why is pay in PE not significantly more than HF on average (perhaps assuming rate of return and fee structure are similar) ?

Does it have to do with the expenses of doing PE... are some of my claims I made here incorrect?

Thanks!