Normally if you are going to ollie (or jump) your tips go into the air first. Nollie is when you start with your tails instead. Lip is short for lipslide, which is bringing your tails over a rail instead of your tips when you are coming from either side (as opposed to straight on).
Now, when you are getting onto a rail from the side, its easier to go with your tips forward because you are doing a normal ollie, with your tips off the ground. When you nollie, your tails are off the ground so its easier to do a nollie lip.
A nose butter is when you are skiing normal and do a revert to switch, keeping your tails off the ground.