How to do awk comparison in TCL -

how use awk 'fnr==nr{a[$2];next}!($2 in a)' b in tcl.

when ran using exec awk {fnr==nr{a[$0];next}!($0 in a)} m1 m2 > diff, giving out nothing in diff.

i want compare m1 , m2 file , different should dump in diff.