A major difference is that VCs (good ones at least) specialize in startups in a given sector and have some understanding of the sector, the product, the market landscape, the culture, etc. They also operate in that sector long term which means they really want to maintain a decent reputation among founders, employees, and even customers. VCs really don't want to get their name associated with "OMG run away!" since it could adversely affect their deal flow in the future.

PE usually doesn't have any special connection to your sector or community. They just buy stuff and try to run it according to bog standard MBA rules.