meaning - Difference between "I am really sorry" and "I really am sorry"

I know they are slightly different, but I can't tell how.

I've read about the usage of the word "really" in a negative sentence. But it didn't tell me about how the position of the word "really" can affect the meaning in a positive sentence.

I've heard sentences I'm confused about:

• I am really sorry


• I really am sorry

And these are the ones I've made up myself (I don't know if this kind of sentence exists):

• She can be really persuasive


• She really can be persuasive

How do I tell them apart (the grammatical structure)? Are they different in meaning too? How?

Answer

In 'I am really sorry', really is an intensifier. You can replace it with very.

'I really am sorry' is a reassurance: you are not saying how sorry you are, just that you are definitely sorry.