Answer:
An alien is a person from a different country that is not a citizen of the host country. Usually, they will only stay a little while in the host country before leaving.
An immigrant is also a person from a different country. They may or may not be citizens, however, the main difference is that they will live in the new country.
Step-by-step explanation:
For a more detailed explanation: look up "Alien vs. Immigrant - Difference and Comparison" on diffen.com.
Hope this helps and good luck on your homework!