Rating:
These files are the same...
- stephencurry396#4738
The description actually tells you pretty much exactly what to do: find the difference ^^.
You can just use the UNIX diff command to do that for you:
diff file.txt file2.txt
106526a106527
> C
107719a107721
> Y
108477a108480
> C
109644a109648
> T
109873a109878
> F
110293a110299
> {
111434a111441
> S
111715a111723
> P
111969a111978
> O
112285a112295
> T
112548a112559
> _
113046a113058
> T
113525a113538
> H
114286a114300
> 3
114773a114788
> _
115594a115610
> D
116750a116767
> 1
117691a117709
> F
118643a118662
> F
121288a121308
> }
...
... et voilà ... the flag was: CYCTF{SPOT_TH3_D1FF}
