Which one should I use? and is there any advantages to each or are they both the same?
They are both very similar. For the application season just now ending, I would say the biggest advantage for either side is that more institutions participate in the Common App than the Coalition App.
If you plan on using only one, it should probably be Common App for that reason.
Check to see which applications the places you want to apply to are using. You might find out that you need to file both.
My D has one school that required the coalition app so she had to do both. The common app was much more user friendly, especially for her recommenders. It was a few cycles though so maybe they‘ve worked out the kinks.
I preferred the Common app…but some schools are only coalition
My S20 had to do both. One school only took coalition, while all of the others took common app. He wasn’t going to give up a school just because it was a different app.
Many schools also still have their own app, so check that too.
Common app is more straightforward, so if you can avoid also completing the Coalition app that would make things easier.
Check with your high school counselor to see if there is one they like to work with more. My counsellor for example only uses common app.