All of those phrases mean the same thing when you want to say a polite sorry (like when someone's in your way or you walk into someone). "Sorry" (and "forgive me") can also be used for a more sincere apology, but in the context of those other phrases, it is simply another way of saying "pardon me", or "excuse me".

Pardon me and excuse me are almost the same. In normal everyday culture, you would use them if you were interrupting someone and want their attention , or to ask to get past someone in a crowd. Excuse me is used more often than pardon me. Forgive me - That would usually be reserved for asking forgiveness if you were to do something wrong to someone. you would ask for forgiveness. Like if you lied to someone and they found out, or you forgot a family members birthday. Usually reserved for some big mistake. Sorry - can be used in many ways!! For simple things, like if there was a little confusion when you try to walk past a stranger, you would just say 'sorry' in passing. Or if you accidentally knock something over that belongs to someone else Or if during a conversation with a friend, you say something to offend someone ' sorry, I didn't mean it that way' Or even being honest, you can use it to mean that you do not mean to offend someone "I am sorry to say, but you smell bad" :)

They all mean the same, but we use certain phrases for certain things. Say "excuse me" when: You want someone's attention. You walk into someone. You want someone to repeat what they said because you didn't hear them (you may also say "I'm sorry"). Your body makes an unwanted sound. pardon me=excuse me "Sorry" is a very important word. Do not use it too much. If you made a mistake and you feel bad about it, say, "I'm sorry." This will mean a lot to the person. The person may or may not forgive you. If they forgive you, they will usually say, "It's okay." If they say nothing, you may say, "Will you forgive me?" The person will say, "No" or, "Yes. I forgive you."