Well, to keep it simple, pumpkin is one type of squash and squash generally refers to four species of genus cucurbita, including the species to which pumpkin belongs. So, to make it clearer, both squash and pumpkin belong to the same family (the cucurbitaceae). A pumpkin is a type of squash. Squash is considered a fruit and it grows on a vine. Here in the US and Canada, we usually break down the squash family to winter or summer squash, depending on when they are harvested.