Would you say the difference is simply the crust vs lack of one?
This is the way I understand it:
frittata – an omelet resembling a large pancake and containing vegetables, seasonings, and often ricotta, Parmesan, or other cheese.
quiche – a pielike dish consisting of an unsweetened pastry shell filled with a custard and usually containing cheese and other ingredients, as vegetables, seafood, or ham
So yes and no…yes quiche uses a pie crust and no a fritatta is usually vegatables and cheese whereas a quiche often uses seafood or ham.
In reality I have seen so many variations of both and they can all be interchanged to one’s own tastes.
Yeah, it’s complicated. That’s why I asked.
Omelette - Fried eggs, maybe some ingredients folded into it after the eggs are cooked.
Fritatta - Omelette, with ingredients mixed into the eggs.
Quiche - Fritatta with a crust.
But then things get ugly like diet quiche with no crust, use bread and it’s a strata, could be a casserole even…
I’m sure the capster can shed some more light on this subject. 
The difference isn’t just the crust; it’s what you do with the eggs. A quiche is made using a custard (cooked cream/milk and eggs) while a frittata generally just uses eggs. So the texture and flavor is much different since a quiche has a creamy, custardy component that a frittata lacks – that’s what I see as the key difference much more so than the crust.
You can probably find frittata recipes that use cream, but look at the ratio of cream/milk to eggs in both recipes. In a custard, the eggs (or egg yolks) are a thickener for the cream/milk. In a frittata, the eggs are the binder for the ingredients; if it uses cream, it’s just to add some richness (like in scrambled eggs). I tend to think of frittatas as being denser, or having more other ingredients in proportion to the eggs than the other ingredients in a quiche. Frittatas seem to have the consistency of scalloped potatoes, while a quiche is sort the consistency of a flan with stuff in it.
I think crustless quiches are kind of a lame idea. Diet quiche? YGBFKM. You take something loaded with eggs, cream, cheese and bacon (a quiche lorraine), and you think losing the crust will cut significant calories? That’s like saying “I’ll have the 24 oz porterhouse and a diet coke”. Cut a smaller piece and have it with a salad, but if you’re going to do it, at least do it right. If you want diet and eggs, make an egg white omelet instead.
The difference isn’t vegetables either. Asparagus and gruyere quiche is a great dish in the spring. Broccoli is popular, as are onions.
DROOL Frittata
With Asiago, cherry peppers, potato, onion and crumbled Italian sausage.
Try the ingredients for a Denver Omelette (diced ham, onions, green pepper, and cheddar cheese) in a fritatta some time. Really tasty.
True that a fritata does not get a crust, but the real difference is the texture of the eggs. A quiche filling is dense and custard like as bluesman and gordon said. A fritatta is supposed to lighter and fluffed up. This can be achieved with a whisk. Beat the eggs to incorporate lots of air into the egg mixture and then pur them over your other ingredients just before cooking.
To give the eggs an extra push to make them rise and be fluffier I throw in a little baking soda when I beat them. Works great.
A lot of fritata recipes have bread in them, even pasta sometimes with the eggs baked on top like a kugle.
Too ugly for pictures! But it tasted awesome. Homegrown taters, peppers, onions, tomatoes. Ham, swiss, cottage cheese, sour cream, cubes from a loaf of rye I made a few days ago. Few shakes of some various spices. Baked it in a cast iron skillet. When I flipped it out, one corner stuck and wrecked the whole thing. Thus no pics.
oh yeah, there were eggs too. (9)
Heart warming food IMHO. Nothing better than a freshly made fritatta on a Sunday morning.
The best thing about them is that your not locked into making them with specific ingredients.
Use what you have on hand. I like mine with onions, peppers, mushrooms, ham or sausage and good Wisconsin or Vermont Cheddar Cheese…a good pinch of some Season-All and shazaam!
Damn how did I miss this one?
I’m a fritatta man… and mine never stick. Oftentimes, when I got a cup or so of leftovers- particularly pasta in sauce like rotini or gemelli it’ll get done as a fritatta. Makes a great filling. And I like them a little crispy so they get done thick in a small skillet so as to not dry out. Hot on the range till it bubbles around the edges and then it goes in the oven until done through.
I like those little premade mini-quiches when they’re free.
Who taught you guys how to cook?
You’ll always be better cooks than I’ll ever be :-\
Hunger is the best spice…
It’s a “food of love” as Emiril Lagasse says. If your heart is in it and you have the willingness to learn it will happen.
If you can brew good beer you can cook good food.
So, the stove first crusts it up so it doesn’t stick? I had olive oil under the bottom layer of taters and pats of butter all around the edges - thought I was good. 
Got cable? Put on food network while you’re surfing this site. Adopt bits and pieces from food network, a little from here and BAM! you’re better than 95% of the population. Not much different than beer, and the payoff is much quicker.
Rub the oven pan with butter, then dust it liberally with flour. Then put in the filling and top with eggs. Shouldn’t stick at all then.
FLOUR! D’OH!
Exactly! I just heat the pan and oil up over medium heat and pour the mixture in. Doesn’t take too long before it is ready for the oven.
Something I’ve always wanted to try is shirred eggs.
Sounds easy enough to do - why don’t you? Just avoid the eggs with salmonella 