Apologies and thanks

Thank you

• 고마워.
  • 고마워 is a low form of "Thank you." 고마워 is used among friends or to people who are younger than you.
  • and you can say "땡큐" among friends.

• 감사해.

• 고마워요.
  • 고마워요 is used among peers (like co-wokers...) or to junior or younger than you.

고마워요 looks like honorific form but it is close to low form.

so if you use 고마워요 to senior or to people who older than you, they'll feel bad.

• 감사해요.
  • 감사해요 is hardly used.

• 고맙습니다. 감사합니다.
  • 고맙습니다 and 감사합니다 are honorific form of "Thank you". 고맙습니다 is pure korean, 감사합니다 is Chinese roots word.

Grammatically, 고맙습니다 and 감사합니다 are same level of honorific form. But many people consider that 감사합니다 is more honorific than 고맙습니다.

• • 고맙습니다.

to older than you

customer → clerk

• • 감사합니다.

to older than you

clerk → customer

grandchild → grandfather

student → teacher

Sorry

• 미안해.
  • 미안해 is a low form of "I'm sorry ." 미안해 is used among friends or to people who are younger than you.
  • and you can say "쏘리" among friends.

• 죄송해.

• 미안해요.
  • 미안해요 is used among peers (like co-wokers...) or to junior or younger than you.

미안해요 looks like honorific form but it is close to low form.

so if you use 미안해요 to senior or to people who older than you, they'll feel bad.

• 죄송해요.

to older than you but close person

to close senior

to close boss

• 미안합니다.

to stranger (but looks like younger than you. for example, middle age person → young person)

• 죄송합니다.
  • very polite form

clerk → customer

employee → boss

to stranger (for example, when you bump into a person on the street)

student → teacher