Summer squash and Vegetable marrow

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

Vegetable marrow and summer squash are semantically related. In some cases you can replace phrase "Vegetable marrow" with "Summer squash", this phrases are similar.

Vegetable marrow noun - Any of various squash plants grown for their elongated fruit with smooth dark green skin and whitish flesh.

Summer squash and vegetable marrow are semantically related. You can use "Summer squash" instead a noun phrase "Vegetable marrow".