I'm told they're all in the same squash family. Also sweet potatoes can be used instead of pumpkin. The nice thing about say butternut squash is you can buy or grow it and keep it in a nice cool dark area and it will last for many months, not like pumpkin that seem to deteriorate faster. Don't know about the Acorn or spaghetti squashes though. I grow the butternut and my sister grows the pumpkin when she can keep the deer out of her garden. We've kept it down in our basements for over a year without having it go bad.
This year, though it wasn't my best year for squash, I gave all away as I still have 5 - 1 gallon freezer bags in the freezer for my soups.