Both movies have like a summer setting and are very beautiful and honestly also kinda poetic, they just have a similar vibe. Both leads have a crush on their best friend.

Both movie have a bullied gay male main character, who comes across a dead body on a field. Things go kinda crazy

Both movies include an lgbt couple with a kid, who have to face discrimination and prejudice. I guess the endings are also both left rather open.

Both main male leads have wives and supposedly happy lives until they start a forbidden affair with someone much younger than them. That other person falls in love HARD and doesnt mind going to great lengths..

Both of these movies are bat shit CRAZY at times. They also include characters that are so mad in love with the main protagonist that they go to crazy lengths. Its also left to own interpretation if it was one sided or requited

While they handle lgbt issues differently (close knit adresses lgbt issues while in how to win at checkers nobody seems to have a problem with lgbt+) they include lgbt characters.
Both movies focus on an 11 year old kid (the child actors did an amazing job!) and both are incredibly heart breaking

To me they had a similar feel and atmosphere. The two movies are very different in terms of subject matter and story in general (also how to win at checkers doesnt include straight up homophobic characters). They crush you, both are dramatic bur have some nice moments sprinkled in between.

-The characters go through so much and you just want them to be happy.
-both are realistic
-they hit you in the feels
-both are rather slow
-the characters go through "similar" situations
The settings are very different from eachother and Night Flight is more brutal but if you enjoyed one you might also enjoy the other