Well, if you're going to be technical about it, there's really no such thing as a "pumpkin". That's just a name people have come up with to describe large, orange squash. But a pumpkin is a winter squash. Squash and gourds are in the same family though. So you're right, a "pumpkin" isn't technically a squash in the same way a radish isn't a turnip. Very closely related and in the same family, but slightly different.