Please help...

I have a really big spreadsheet and would like to find all the unmatched
information when comparing two columns in a spreadsheet. Is there any
formula or functions to perform this checking, or is there any methods
suggested?

Example:
Info listed In column A: red, blue, green
Info listed in column B: blue, violet, black, yellow
Result (unmatched info) after comparing column B to column A: violet, black
and yellow