Both are set in high school, and are cantered around a weak student becoming strong to fight, alongside their strong friend, against bullies..
Both are comedic

Both are bromances
Weak Hero may be the nicer show, however the friendship in Boys Be is more homoerotic (in my opinion). There are kinda innuendoes alluding that they’re lowkey more than friends. Kind of like a censored BL.

They’re both queer films
They’re both about young love that reunite when they’re older
I’d say YNEH is a bit more bittersweet than SLSYT