they sound pretty similar in their effects. ie higher % = typically better table. however, one difference would be that VPIP would count limp/folders in the %, whereas % of players seeing the flop would not, as limp/folders don't see flops, obviously. not sure what to infer from that as regards strategic table choices....
also these stats may be quite ineffective/borderline redundant, as !Luck pointed out, depending on how many hands prior to the current one the sample is drawn from.