No. "Nah" and "no" mean the same thing. "Nah" is often followed by "man." As in "nah, man."
-Person 1: Do you wanna go to the movie theater?
-Person 2: Nah.
OR
-Person 1: Do you want to go strip in front of my neighbor's house?
-Person 2: Nah, man. That's just gross.
By Elianora
Nah
Used when "no" is too formal, and "nope" is too casual.