@foo = (1, 2, 3, 4, 5, 6, 7,  8,  9,  10);
@bar = (0, 1, 2, 5, 7, 9, 11, 12, 13, 14);
my @diff = grep {my $baz = $_; ! grep($_ == $baz, @bar)} @foo;
print join(",", @diff);

Gives:
3,4,6,8,10