compare two tables with a formula

Hi all !
I have a problem that I need to solve in Excel.

I import using a VBA script two files with students name and grade and I wish to know if each student exists in the second table and if it has a different grade.

For example, look at the attached file (ex.xls and ex.jpg)
I have 2 tables near each other.
John is only present on the first list (so "not found" appears next to it).
Lee has the grade of 60 on the first table whereas 70 on the second table so "changes" appears on both tables.

Can you please help me to create a formula or anything like that ?
Also, This formula needs to run on 2 tables (table 1 compares to 2 and 2 to 1)
The tables have around 2000 entries so it has to be efficient.

Thanks for your help !!

Paste into B2 and copy down.

=IF(COUNTIF(D:D,A2)=0,"not found",IF(B2<>VLOOKUP(A2,D:E,2,0),"changed",""))

Paste into F2 and copy down.

=IF(COUNTIF(A:A,D2)=0,"not found",IF(E2<>VLOOKUP(D2,A:B,2,0),"changed",""))