What is a dinner suit?
A dinner suit is often referred to as a tuxedo and there are several major differences between a dinner suit and a stock-standard suit:
Dinner suits usually feature a satin face on the lapel. They also have a matching satin stripe on the trouser which runs down the outer seam of the leg. This stripe is kind of falling out of fashion, however, it's not really that essential.
Tuxedos are usually worn at “black tie”-coded events as they are predominantly black and worn with a white dinner shirt and black tie or bow-tie. But really, as long as you have the satin on the front of the lapel it can be any colour you think you can reasonably get away with.