How do the batter and technique differ between crepes and pancakes?

Crepes do not contain baking powder or baking soda for leavening. They also typically use melted butter vs. oil in pancakes and have a higher liquid to flour ratio. Basic crepes contain only eggs, milk, water, a pinch of salt and flour.

You can however make them more sweet or savory by adding chopped herbs or a bit of sugar (not too much or you'll have too much browning), cocoa powder, spices such as cinnamon, nutmeg, ginger, etc.

For additional help & recipe for Black Forest Cherry Crepes: Tips for Successful Crepes

The thing to remember about crepes is, unless you are very good (I am one of the lucky people who is; some people are and some aren't, it has absolutely nothing to do with skill), you will lose the first one 'to the pan'. It just won't turn out right.

To cook crepes properly you need a medium-hot nonstick pan and a good offset spatula. Throw a tablespoon of butter into the pan, melt it, swirl it around to coat. And then pour the butter out. Yes, really. Add a ladleful of your batter, and twist the pan around to coat the entire bottom. Cook until set (French style, colourless crepes), or until you see a tiny bit of crisping around the edges (alternate style, gives you a lacework pattern of golden brown across the whole thing), then using your offset spatula, flip. (Or if you're very good which I am not, flip in the pan). Each crepe should take about a minute or so. It's very easy, once you get into the rhythm, to generate a stack of crepes very very quickly.

It's similar to making pancakes, but it's a much more delicate process.

I think it's the thickness that differ the two. I have a very great crepe recipe here, which has been favorite. Pair it with Grand Marnier, an orange flavored liqueur, and you're good to go.