Using Excel 2010,

1)  Load both files
2) copy the older table and paste it to the end of the newer table
3) In the Data Tab Click Remove duplicates

 4) you will be prompt with this:

 The column names will be obviously different depending on what you have as a header.

Select only a combination of Unique data so for example in this,
I would select just emails.

You can also select First and Last name,  But then there is a chance that in a large sets of data that 2 different people will have the same name.  Email is usually unique.

If this helped you, please leave a comment. Consider getting me a cup of coffee,  follow this link:  goo.gl/0cg2uu     Thanks in advance!