What is the difference between Flies and Insects?

The difference between flies and insects is that “flies” is any insect of the order Diptera; characterized by having two wings , also called true flies and “insects” is an arthropod in the class Insecta, characterized by six legs, up to four wings, and a chitinous exoskeleton.

What is the difference between Mayflies and Flies?

The difference between mayflies and flies is that "mayflies" is any of the many fragile insects of the order Ephemeroptera that develop in fresh water and live very briefly as winged adults and "flies" is any insect of the order Diptera; characterized by having two wings , also called true flies.