my %results;
open my $fh1, "<", "file1" or die $!;
while (my $line = <$fh1>) {
    chomp $line;
    $results{ $line } = 1;
}
open my $fh2, "<", "file2" or die $!;
while (my $line = <$fh2>) {
    chomp $line;
    my $part = $line;
    $part =~ s/\..*//;
    unless ($results{ $part }) {
        say $line;
    }
}