Two invitations, two very different evenings. Here is how to read them.
It's about the bow tie
Black tie refers to the men's tie, born with a Savile Row dinner jacket in 1865. It says nothing about the color of your dress.
Floor length is the standard
A formal evening gown. A very dressy cocktail dress is the minimum.
A little more freedom
Floor length is still the safe choice. A dressy cocktail dress or evening separates are also correct.
One strong detail
A slit, a neckline, crystals or lace. Choose one and let the rest stay quiet.
From Maria's edit
Gala season is coming. Start with one perfect black gown.