Could you please explain?

"NV" is just the term used for perl's floating point type.
Depending upon how perl was built, it could be either a 'double', a 'long double', or a '__float128'.
$Config{nvtype} tells you which type the NV is.
$Config{nvsize} tells you how many bytes are allocated to that particular type.

If nvtype and nvsize don't change from one machine to the other (as is the case with your machines) then arithmetical operations should produce identical results.
If the configurations match (wrt nvsize and nvtype) and identical arithmetic operations produce different results, then at least one of those machines has a bug.
Such bugs do exist - but they're relatively rare. (On perl-5.30.0 they're even rarer.)

Cheers,
Rob