Wow Natalia, that is a great question, and one that I have never heard before!
Well, there is no particular sign that says "table service" or "quick service" that I am aware of in the restaurants. Basically, if you order at a counter, then you are at a Quick Service restaurant, and if someone waits on you, it is a Table Service restaurant.
But here is a surefire way to know for certain. If you go to
this page at the Disney World website you will see some printable PDFs of the Disney Dining Plans listed under "Related Resources". The standard one (Called "Dining Plan") lists all the restaurants on the Disney Dining Plan (which represents just about every restaurant, with only a handful of exceptions). Next to each is an icon that tells you if it is a Quick Service restaurant or a Table Service restaurant.
I hope that helps! If not, send me a follow-up question and I will try again!
Have a Delicious Vacation!