AOG
Not really one word.
As a civil partnership isn't a marriage, then the partner cannot call themselves husbands/wives. They would have to call each other 'partners' which doesn't imply marital status (and the term 'marital status' doesn't apply).
They can never say "I got married back in..". They instead would have to say, "I entered a civil union back in...", which about as romantic as "I signed a contract for an extended warranty on my washing machine back in..."
They cannot go on honeymoon, because of course, you go on honeymoon after getting married, and gay people are not allowed to get married.
The whole language of marriage and commitment is excluded from gay people as it stands. Instead, CPs are a fake version of marriage. You can dress it up to look like a marriage - you can have best men and bridesmaids (except of course, you don't have a 'bride' at a CP, you have a 'female contract signatory'), but it's still not a marriage.
However, if indeed you say that it's just words and it shouldn't matter - then I assume that you agree that gay people should wed. I mean...if it's only words and it shouldn't matter, what's the fuss all about?