////"Mass or weight makes no difference since gravity acts on them exactly the same way."

Gravity only acts on 'Mass' - it cannot act on Weight'. It is already PART of 'weight'. :-)////

The "them" I was referring to were the nucleons not the quantities of mass and weight themselves.

It was not correct of me to say weight since mass can remain constant even if weight changes. The change I am talking about is actually a change of mass (which will still change the weight). The mass of a nucleus is less than the mass of its constituent nucleons weighed separately and added together (we still say "weigh" when referring to determining mass as your ordinary bathroom scale determines mass rather than weight but we still "weigh" ourselves on it).