There are two products basically: wax and paint sealant. The latter is just a synthetic wax that goes on a bit more easily and tends not to leave white crusty bits on the crevices. They behave differently; wax repels water more vigorously but doesn't usually last as long (maybe 2-3 months if left out in all weathers) as sealant (6 months). Also, the best waxes give a deeper shine than sealant, although there isn't much in it. Carnauba wax usually gives the best "wet look" shine. Silicone waxes are easier to apply.
Confusingly, Meguiar's NXT sealant is called "Tech Wax". There's a lot of marketing guff behind car waxes. I've never found one that doesn't work, but the aforementioned NXT smells nice and is fairly easy to apply and buff off.