Had both and I much prefer #4. Mainly because I hate shooting up with citric or vinegar because a miss hurts like a bitch, but the #4 always brought a better buzz and rush with it. The #3 I got was pretty bad quality, however, whereas the #4 I get is da kitties titties. I prefer #4, but I feel like if you got decent #3 then they should be the exact same thing. Guessing my experience was mainly due to quality.