Another one that has been languishing in my askbox! Apologies for that.
This is very off the top of my head since I don’t really feel like going back and reading Act 6 again, but here we go—
John and Jake’s main similarities are their appearances (messy hair, glasses), their love of bad movies, and how much they care for their friends. That’s not very much!
Jake is very earnest. He doesn’t love bad movies despite them being bad or because they’re so bad they’re good, he loves them wholeheartedly and unironically. He’s pretty artless, and what guile he does have is usually transparent.
John, however, is mischievous. He likes to play pranks, indulge in word games, and tease his friends. He has some awareness that the bad movies he likes are widely seen as pretty bad. He also seems to understand his friends better, whereas Jake doesn’t really understand and thus can’t predict his friends’ emotions. He cares about them just as much as John cares about his friends, but he’s much more obtuse.
Both boys are passive, but John is passive in the ‘go where the wind blows him’ sort of way, not taking control because he doesn’t really want to, whereas Jake gives the impression of wanting to be active, but not really knowing what to do or how to do it (that seems to be a very Page thing). Look at Jake’s incarnation as Grandpa Harley — he was a guy who did things with great gusto.
John and Jake are more contrasts to one another than anything else.
[See also this little bit of discussion!]