How to distinguish between different types of squash? Last spring I planted two seedlings that claimed to be pumpkin. They've grown long tendrils and lots of leaves, and have made several flowers, and I thought that was that (I subsequently found out you're supposed to pollinate pumpkin manually). 

Having now cleared some of the weeds from around them, I've discovered that they have in fact fruited. 

One plant has two fruits - both very dark green, spherical, one about 3" or 4" diameter and the other one about 6" diameter. 

The other plant has two fruits - both yellow, spherical, about 1" in diameter. 

Are these in fact pumpkins or maybe some other sort of squash (presumably it's possible the two seedlings are not the same variety)? How can I tell? How can I tell when they're ready to eat? Will the mini ones continue to grow now the weather has turned cold and wet?
If you want to post a picture somewhere I can probably tell you. 

You could do a cursory google image search and see if visually you can tell what they are. I have grown pumpkins most of my life and I have never manually pollinated them, I have never grown the "big ones" though so maybe that could be different. 

Pumpkins in the southern US generally ripen closer to late september-to-mid-october and can hang on the vines for a bit. It sounds like you have some veriety of squash. If you do have pumpkins unless they are an off shoot hybrid they should be taking on their orange color by now, especially if you planted them in spring. Having said that if they did not get enough water or enough heat then their growth would be stunted. It could be your yellows have stunted and are shriveling but I would assume they look healthy.