Sometimes we refer to both zucchini and squash as summer squash which can be quite confusing. However, there are some basic differences.   Zucchini (also known as a courgetti) is usually green in color and relatively straight in shape and has a little bit less seeds compared to a yellow squash.  Yellow squash is usually bright yellow in color and can have a straight neck (younger) or have a crooked neck (more mature with more seeds and external bumps). We find that they have a few more seeds compared to a zucchini. If you want a mellow tasting yellow squash similar to the taste of a zucchini, choose the straight neck younger yellow squash.