This is actually a question to study with a dictionary.
Act is defined by Dictionary.com as:
1. anything done, being done, or to be done; deed; performance: a heroic act.
2. the process of doing: caught in the act.
8. false show; pretense; feint: The politician's pious remarks were all an act.
(Note that I removed the legal, theatrical, and philosophical definitions in the above.)
Action is defined as: