Comparing 2 worksheet s or ranges

[Lin Mon]

Hi There,
I want to write "if statement" by comparing the contents
of 2 worksheet in different workbook (file). The contents
include text and number.
I also want to compare the contents of 2 ranges in
different workbook. Number of cells in each range are the
same.
If someone can give me the syntax or any clues, I will be
appreciated very much.
Thank you,
Lin