Buck is the informal term for a dollar. Slang: A "clam" is one dollar A "sawbuck" or a "ten spot" is a ten-dollar bill. A "big one" and a "grand" mean 1000 dollars. Also 10 "large" would mean ten thousand dollars. A "C-note" is a hundred dollars (mostly a hundred-dollar bill). It comes from the Roman C = 100. Another name for a hundred-dollar bill is a "Franklin", since Ben Franklin's picture is on the bill. "Scratch" is a slang term for money in general.

To add on to the response from fdmaxey, "buck" is an informal (slang) term for a dollar. Based on your profile, I see that you are from China. This distinction might make more sense if you consider the following analogy: Formal name: United States dollar is to Renminbi (人民币), as Common name: Dollar is to yuan (元), as Informal name: "buck" is to kuai (块)

bucks and dollars are same. Actually bucks means some kind of animals. but in some nations the term bucks is used instead of dollars.

dollar=buck