Black Tie Ball -help please.

[MustTidyUpMustTidyUp]

So.... What does it actually mean?
DH. - does he need a dinner suit? Is a normal dark suit ok with a dress shirt and bow tie?
Me - i have this or this but it's nicer than looks here are either suitable or am I way off the mark?
I prefer the navy on fwiw.
I have more questions but will get to them...
TIA

Thanks Dotty I will go with the navy one. I already have these dresses and would prefer to not have to buy something new.
Could you help me accessorise it? Not really sure what to put with it.
Thanks

The navy one is lovely - have a lovely time

I've noticed at the past few balls we've been at, that lots of men (mostlty younger) seem to opt for a tie instead of bow tie.