Pumpkin and Summer squash

Pumpkin noun - A coarse vine widely cultivated for its large pulpy round orange fruit with firm orange skin and numerous seeds; subspecies of Cucurbita pepo include the summer squashes and a few autumn squashes.

Summer squash and pumpkin are semantically related. In some cases you can use "Summer squash" instead a noun "Pumpkin".

Summer squash noun - Any of various usually bushy plants producing fruit that is eaten while immature and before the rind or seeds harden.

Pumpkin and summer squash are semantically related. You can use "Pumpkin" instead a noun phrase "Summer squash".