Can I use yellow zucchini instead of green zucchini in vegetable soup or is there a significant difference of between them?
In general, they are interchangeable unless the green color matters in your presentation. Texturally the differences are insignificant.
I've used patty pan squash, yellow summer squash (yellow zucchini), and regular zucchini interchangeably. There may be slight differences in sweetness or texture, but not enough to make your dish fail.