White Tie invite: Eveningwear: Also known as Full Dress, the white tie and tails is the most formal of all clothing. Attire set aside for high society and ball room dancing.
Corporate Black Tie
Corporate Black Tie Invite: Eveningwear: As a guest or a sponsor to a Corporate event, you are being asked to wear a Black Tuxedo, usualy with a Black Bow Tie and a Black Vest or Sash, for the more conservative attire .
Wedding Black Tie
Formal or Black Tie Wedding/Party Invite: Eveningwear: Here your Host is requesting you to wear a Black Tuxedo. But unlike the Corporate Black tie, you may have some Fun with Styles or Colors. Perhaps a Neck Tie to match your Escotr's Dress color. Or a Silver Vest just for some contrast.
Semi/In-Formal
Semi-Formal Invite: also can be called In-Formal: Dark Suit: Usually not stated on the invitation, but is usually asssumed when invited to a wedding or dinner.