Delicata squash first originated in Central America. Part of the Cucurbitaceae family, these squash are similar to acorn squash and are able to cross-pollinate with pumpkins.
Acorn squash is part of the Cucurbitaceae family. This squash is further part of the Cucurbita pepo group along with a variety of other summer squashes.
Zucchini originates from Central America and Mexico. It is part of the gourd group, and overall the Cucurbitaceae family, along with several other types of squash mentioned.