The only difference I notice is that the 4 hole as easier drag - vapor output is about equal. I don't know about reliability though which is a benefit Cash gave for the 4 hole... anyone else share comparisons of the two? Also, from watching Leaford's review of e-cig.com's penstyle, apparently Cash's batteries are of the same quality as njoy's which may be why his two-hole produces such great vapor in my experience. Anyway he's probably only selling 4 holes from now on so it don't matter much .