Tagliatelle is pasta that, like fettuccine, is long ribbons of egg pasta, but that is slightly narrower than fettuccine. Italians will often use tagliatelle with a meat sauce.
In North America, usually sold curled in “nests.”
For a southern-Italian version of tagliatelle with no egg in the dough, see Lagana.
Fettuccine (narrower); Pappardelle (wider); or just plain old spaghetti.