crunchy v.s crispy

Crunchy is the word we use to describe the sound of something heavy and thick being ground or chewed. (Imagine the sound you hear in your head when you eat nuts or French bread. Or the sound you hear when you drive a car over thick gravel and you can hear the rocks breaking. That's a "crunchy" sound.)

Crispy is the word we use to describe the sound of something light and thin when it is being ground or chewed. (For example, the sound you hear when you bite a cookie or biscuit. Or what happens to bread if you leave it in the toaster too long. It comes out "crispy.") 



Apple - either; Chocolate - neither; Dorito - either (crispy more usual); Popcorn - crunchy; toast - either, but not often either; Fries - crispy, some cereals - crunchy; cold iceberg lettuce - crisp

Perhaps the more flat, thin, and paper-like (two-dimensional) a thing is, the more likely it will be crisp, not crunchy. crisp often connotes something more delicate than crunchy does. It's closer in meaning to brittle. crunchy often connotes something solid and sturdy in comparison. 
the snow under your feet when the air is still and extremely cold - The snow crunches under foot.
In autumn the dead leaves crunch under foot.
the air on a cool autumn day - feels brisk or crisp
a food item that has cooked much too long - fried to a crisp
the sound of two automobiles ramming into one another (an accident) - Crunch!
the way a person responds to a question when annoyed or slightly angry - crisply 
CJ