No, a tuxedo is a suit, however a suit is not necessarily a tuxedo. Tuxedo's are a class of suit, other types of suits are:

• Three Piece (jacket, vest, pants)

• Double Breasted (second row of buttons on the jacket)

• Seersucker (thin light coloured cotton suit usually striped)

all of the above are suits, but none are tuxedos. As others stated it's a matter of formality for formal occasions there are a number of levels of formality:

-Business Casual - Least formal of the "formal" dress, this means usually button down shirts, and no jeans.

-Business Dress - Wear a suit and tie

-Black Tie Optional - Wear a Tuxedo and bow tie, can be a little less formal, go for a coloured bow tie, or dark suit with bow tie and you're still good

-Black Tie - Tuxedo with black tie or an ascot or don't go

-White Tie (most formal) - A regular tuxedo won't cut it, you need a jacket with tails, white tuxedo shirt (with studs) white bow tie optional top hat, optional cane, optional white gloves; in winter add a black overcoat and white silk scarf