went to the nursery and tried to find the stuff there. Closest I came to was Applemint. It's not Catnip, it doesn't look like the stuff they had at the greenhouse that was Catnip anyway. It has a kinda pleasant smell actually, I will have to go back out there and smell it again...LOL
Lemon balm has a much more scalloped edge leaf. I vote catnip (or maybe a natural cross between the two?) Lemon balm is a distinct mint/lemon smell. It is a very light green (almost chartreuse) when it first emerges.
I don't think it is lemon balm-mine is dark green, somewhat shiny and has a very heavy lemon scent. I think catnip smells more like urine or medicine and is more gray and hairy. I'm trying to remember what horehound looks like. I killed mine. LOL I can send you a pic of my lemon balm or catnip if they aren't in the database. I don't know about where you are but down here we have some sort of wild mint that sort of smells like pineapple and is furry like that. I have never really tried to find a name for it.
This is a tough one and I agree with Poppysue applemint would be my fist choice. I don't know what Sprite smells like but a similar woolly mint with a curious smell (to me anyway) is Bowles mint - Mentha x villosa 'Alopecuroides', some say its an apple/spearmint smell, others say strongly mint or strongly apple, to me it's sort of fruity, fresh. Plants smell different to different people so only Flowox can tell :)