comparing two tables

I have 2 tables(worksheets) of customers' data and need to create another one out of these two.The new table consists of data which is in the first table only.In other words,if the data is in both tables then that particular row is excluded from the new table.Matching key is lets say ssn of the customers.So if same ssn appears in both tables then those two respective rows won't be in the new table.
So how do i do it,how do i compare variables from two different worksheets?