As far as I know there are three different ways to say "thank you" in Korean. Two of them are polite and for anyone who's taken a foreign language, there is a polite way to address an elder.

The first is "Gam sah habb nee dah." This is considered a polite.

The second is "Goh mabb subb nee dah." Nothing is different in meaning, just a different way of saying it like "Hey" and "Howdy."

The third is to one of your peers. "Goh mah wuh."