1. The "team" splits up.
Quill, Gamora and Drax go on a trip without Groot and Rocket. Just like Han, Leia. Chewy and C3PO went on their own adventure while Luke and R2D2 went to hangout out with Yoda.
2. There's a big chase scene through an asteroid field. Pretty simple, but there are asteroid chase scenes in both movies.
3. One team hangs out in a natural forest after their ship crash lands there.
Rocket, Groot and Nebula are in the forest repairing their damaged ship. Luke and R2D2 are on Degobah where they crash landed.
4. While the other part of the team goes to a wonderful place and is in the lap of luxury.
Quill, Gamora and Drax go to Ego's planet, which on the surface appears to be paradise. Han, Leia, Chewy and C3PO literally go to a city that floats in the clouds.
5. The paradise is not what it seems. Ego and his planet try to kill Quill and his team. Darth Vader is waiting for Han and company in the Cloud City. Whoops on both counts.
6. The forest team tries to rescue the part of the team in paradise. Rocket and co. go to Ego's planet to try and save Quill. Luke goes to the Cloud City because his friends are in trouble.
7. The main character has daddy issues. Quill's dad Ego wants him to join him and take over the universe. Luke's dad Darth Vader wants him to join him and take over the galaxy.
8. Both the dads killed the main character's mom. Ego killed Quills mother with cancer. Darth Vader broke Luke's mom's heart when he turned to the Dark Side, which killed her (somehow. Of course, Padme had to have known Anakin had some anger issues, he did kill all the Sand People, even the women and kids).
9. A bad guy turns out to really be a good guy deep down. Yondu turns out to not be too bad of a guy. Lando turns out to not be too bad of a guy.
10. There's significant loss for each team. Yondu dies. Han is frozen.
***SUPER BONUS THING THEY HAVE IN COMMON***
11. They are both sequels that at least some people think are better than the first movie in their respective franchises.
I really hope there are teddy bear looking aliens that turn out to be cold blooded killers (Ewoks) in the the 3rd Guardians of the Galaxy movie.