What is the difference between a collective noun and a compound noun?

Collective noun - a noun that refers to a collection of things. Compound noun - a noun made of two or more words.

Collective : the word "group" is a collective noun, and can refer to a group of boys or a group of people or a group of animals. Collective nouns can also be specific to a group: school of fish, pride of lions, or, my personal favorite: murder of crows.

Compound nouns are nouns made of two or more words, the first one usually modifies the second. For example, blackbird is made of black and bird, where black modifies the bird. Other compound nouns may be blackboard or haircut . Compound nouns may also be hyphenated: mother-in-law or d ry-cleaning are well-known examples.