Pie VS Tart VS Quiche
Pie and tart are regional (North American versus Western European) terms for essentially the same thing.  Some will argue that the pans make the difference (see below), but I don't buy that story.

There are some stylistic differences that appear quite often, but nothing that makes them truly different things:


Pies tend to be deeper, and have more filling
Pies tend to be made in a shallow, sloped sided baking pan called a "pie pan; whereas tarts tend to be made with only a ring, or a tart mold which consists of an outer ring with a removable bottom plate.  Tart pans or rings tend to have vertical sides, not sloped ones.
Tarts usually only have a bottom crust
If the recipe is from France or cooks of a French cooking tradition, it tends to be called a tart; if it is from North America, it tends to be called a pie
Pies often feature a flakey short crust, or a crumb type crust, whereas tarts often feature a pate sucre type crust, but again this is far from universal
Pies are usually served from their pan, where tarts are almost never served from their ring&mdash;this may be as close to a defining difference as there is!


Both tarts and pies can be made in a variety of sizes, including appetizer or finger food sized, personally sized, or family sized.

In North America, sometimes a turnover (like an empanada or pastie, but hand-sized) which is baked or fried is also sometimes called a pie, hand pie, or even fried pie. 

The word pie is also used in England and North America for a class of casseroles made with a top crust, such as shepherd's pie (mashed potato crust), steak and kidney pie, or chicken pot pie. 

There is also the gallette which is a pastry made free form without a pan or mold, by making a crust, adding filling, and folding the sides partially over towards the center.  This is essentially a free form tart or pie.

Quiches are a savory pie or tart whose filling is based on an egg based custard, often with cheese as well.

Oh... and if it is from New York, made with a yeast raised crust, and covered with cheese and hopefully pepperoni, it is definitely a pie :-)