If I were an invisible woman,
I could do everything without anyone being noticed.
和 If I am an invisible woman,
I can do everything without anyone being noticed.
的差別在哪裡？如果不好說明，請提供一些例句。

It should be:
If I were an invisible woman, I could do everything (but I think I prefer "anything") without anyone noticing.

Or...
If I were an invisible woman, I could do anything without being noticed.

You second sentence (using present tense) sounds unnatural for a hypothetical state of being. In these sorts of situations, always use "were".

If I were a woman, I would love dressing up in lots of colorful clothes.
If he were stronger, he might have a chance to win the fight.
If she were closer to my age, I might have asked her out.

Present tense can be used when "if" is used as a substitute for "when", as in:

If I am hungry, I need to eat right away or I get dizzy.
If I feel sleepy, I drink some coffee.

Or for a conditional action:

If he crosses that line, I'm going to take him down.
If she pulls the rope, the bell will ring.