The biggest difference between a regular suit and the tuxedo is that the tuxedo has a satin lapel with a matching satin stripe down the outside of trousers. The lapel comes in three styles: shawl, peak, or notched. The notched lapel has a V shaped indentation on the collar, which is similar to a regular suit lapel. The peak lapel has an upward V shape indentation. The shawl lapel has no indentation, and has a curved shape. Tuxedo jackets are traditionally one-button jackets, though today, some tuxedo styles have two to three buttons. Buttons are cloth covered.
The pants have no belt loops and usually no cuff. Suspenders or a cummerbund is part of the attire.
Shirts may or may not have pleats. Studs or cuff links are necessary for the shirt's cuffs.
The tuxedo accessories include either a cummerbund with the pleats facing up or a vest. Shoes are patent leather. The bow tie matches the cummerbund, and the necktie matches the vest.
Tuxedos are usually black, dark gray or a white dinner jacket with black trousers.
Suits usually have self-faced lapels, which are collars that match the material of the suit. The lapel has an indentation similar to the notched lapel of the tuxedo. There are usually two to four buttons on a suit jacket. Buttons can be made of any material and are not cloth covered. Most formal suits are black, dark gray, brown, or navy blue. Some have pinstripes.
The pants may or may not have cuffs. There are belt loops for a thin dress belt. The pants match the jacket material.
Some suits have a matching vest. The shirt is a basic men's dress shirt, which may or may not have cuff links. Most suits are worn with ties, though some men opt for the bow tie.
Shoes are leather but not patent leather.
When to Wear a Suit or Tuxedo
Tuxedos are for formal events. A white tie event requires a black tailcoat tuxedo with black trousers, a white shirt, and a white vest. For the black tie event, you may wear any style of tuxedo unless it is specified. Tuxedos are required for members of the wedding party, the prom, some charity events, award ceremonies, and the formal night on a cruise.
Suits are worn for business meetings, weddings, funerals, and when tuxedos are not required, but the event is still a formal type of attire.