pouf an other issue, I'm fitting with my script to make it reliable

here is ...
in the reality for the test a and b are equal number c and d are different number

a=ISL
b=ISF
c=INL
d=INF

eg more $d
48922183

if [ "$c -eq $d" ] ; then echo "Sys File sizes match" ; else echo "Sys File sizes differ Errror" ; fi

When I launch this I get the same reply for both case which is wrong a=b and c diff d

I've tryied may possibilities with [[]] and "" and = but no one is working well. any one can help pls?