감사합니다 and 고맙습니다 are formal and polite expressions, but 고맙습니다 sounds more friendly. Ex) Thank you for your help. 도와주셔서 감사합니다 / 고맙습니다. 고마워, 고마워요 are also meaning "thank you" (informal / formal form) . 고마워 is used to your friends, Ex) thank you for bringing my cellphone. 내 핸드폰을 가져와 줘서 고마워. 고마워요 is usually used between aquaintances or colleagues. Ex) you will help my work today? Thank you, Chul-su. 오늘 제 업무를 도와주실 건가요? 고마워요, 철수씨. "감사해요, 고마워요" are little bit polite than "감사합니다 고맙습니다." But in my opinion, 감사해요 doesn't be used for many times.