Help comparing columns in separate tabs

Struggling to find the answer for this:
- Tab 1 contains a set of numbers in column A
- Tab 2 contains a much larger set if values, also in column A
- I want to find out which values in Tab 1 column A are NOT in Tab 2 Column A and highlight them in some way - i.e. find unique values for Tab 1

Try this in B1 of Tab 1 copied down:

=IFNA(VLOOKUP(A1,'TAB 2'!A:A,1,0),"Missing")