I'm so confused with that two words, It's different each others? Or their have a special rules on use that words?
Have is a stative verb.
These are verbs such as has/have, be/am/is/are, like, hate, own, think. They have different meanings depending on if they are in simple or continuous forms.
I have a brother.
This describes a state of being and not necessarily an "action".
I'm having difficulty, please wait.
This describes an actual action that is happening now.