i find the two similar a nouns in some meanings , so sometimes very hard to decide which is appropriate. Can you help me?
Act is very often an abstract description of something that has been done as in: an act of kindness/an act of bravery/an act of stupidity.
Action is if you like a positive description of what has been done as in: His quick action in pouring water on the flames stopped the fire getting worse.
Hope this helps