Variation
Squashs are generally divided into two groups. 
Summer squash, immature fruit that is eaten before the seeds harden and includes:

var.torticollia: Crookneck a club shaped more or less warty fruit with a curved neck.

var. recicollis: Straightneck a smooth club shaped fruit with a straight neck.  

var. clypeata: Scallop a disc shaped ribbed fruit.

var. fastigata: Cocozzelle they nearly cylindrical fruit, normally dark green with pale yellowish green stripes.

var. cylindrica: Zucchini an almost cylindrical fruit that is normally a dark green.

Winter squash, mature fruit that is eaten once fully developed and includes:

var. pepo:  Pumpkin a globose to ovoid fruit that can become a very large and is generally orange/yellow and marrows are similar but smaller.

var. turbinata:  Acorn a globular ribbed fruit that is normally green with yellowish flesh.  

var. ovifera: Gourds appear in many forms and colours and a hard-shelled and durable. Normally grown for ornamental purposes.