for each line in File1,
    look at each line in File2
    and for each of the fields in the current line
        if the field has the same stuff in it as the corresponding field in the current line of File 2 -
            remember it,
        otherwise -
            fuggedaboudit
print out a report of all the stuff I remembered

##</code><code>##

foreach (line in File1) {
    look at each line in File2;
    foreach (field in the current line) {
        if (the field has the same stuff in it as the corresponding field in the current line of File 2) {
            remember it;
        }
        else {
            fuggedaboudit;
        }
    }
}
print out a report of all the stuff I remembered;

##</code><code>##

my @files = ('File1','File2');
my $file;
foreach $file (@files) {
    do stuff with $file ...

##</code><code>##

foreach $file (File1..File2) {
    do stuff with $file ...

##</code><code>##

for (File1..File2) {
    do stuff with $_ ...