What is the difference between a suit and a tuxedo?
There are three main things that set them apart.
First, the difference between a suit and a tuxedo is the presence of satin.
A tuxedo typically has satin facing on the buttons, pocket trim, lapels, and a side stripe down the leg of the trousers. More modern suits today have minimized the use of satin to a thin trim on the lapels and a thin stripe down the pant leg. There are exceptions to every rule, but this is a main difference!
Second, when talking about traditional black tie standards, there are other physical differences like appropriate accessories to wear with a suit and that to wear with a tuxedo.
For most modern tuxedo functions like proms and weddings, the lines have been very blurred like that of every other known style rule today. It’s common, more everyday, to wear long ties and high stance vests with tuxedos, which was traditionally a look only appropriate with suits. Tuxedos are historically worn with bow ties and cummerbunds or waistcoats (low stance vests.)
Lastly, wearing a suit is more of a casual formal look. For instance, if you wear a suit to your wedding there is a good chance people in attendance could also be wearing a suit.
Some people wear suits everyday, and it is completely normal. Where as a tuxedo is more formal, and worn anywhere outside of that special occasion will stand out.