The difference between Sorry and Thank you. You can say thank you to anyone at anytime you want. It doesn't make any difference to your life. Even it makes the other person feel better about you. But You can't say sorry to anyone, You have to be be sorry only when you felt so. Be sorry, only when you have done anything wrong or sometimes we can also say sorry to make someone feel special but that's a very rare case.
We don't have to bow or feel low in front of anyone.