A pie pumpkin, and pumpkins in general, are part of the winter squash family and can be used interchangeably with many different winter squash varieties. There are dozens of varieties of pumpkins ranging in color from near-white to orange to green, too. Varieties that are best used for cooking are generally called sweet pumpkins or pie pumpkins.
If you want a replacement for canned pumpkin, you can cook the pumpkin and puree it. Pumpkin puree is very easy to make. Simply cut pumpkin in half, remove seeds and pulp, cover with aluminum foil, then bake at 350° for an hour or so (until tender). Remove meat from shells and then puree in a blender. If you want to keep it for later, just pour into plastic bags and freeze for future use.
Also, you might want to explore the exciting world of punkin chunkin at the World Championship Punkin Chunkin Association website!