If you just want the lists of users to be added and deleted, it can be done in a few unix commands:

awk '{print $2}' < file1.txt | sort -u > file1.sor
awk '{print $2}' < file2.txt | sort -u > file2.sor
comm -13 file1.sor file2.sor > onlyIn2.sor
comm -23 file1.sor file2.sor > onlyIn1.sor
[download]

and if you want accounts present in both, use comm -12 instead