The major changes are they've changed how Leo comes back into Toby's life. He no longer just shows up at Toby's apartment, but Leo literally runs into Toby, who mistakes him for Adam as he's running out of the Strand, shoplifting books. Then Leo shows up to his apartment to shower and wash his clothes same as before, but this time Toby knows who he is immediately and they do not have sex. They just become friends who see movies and plays. They don't have sex again until they get to Fire Island and there's a new section describing their sex and how it's the first time Leo's had sex with someone else thinking about HIS pleasure and how great it is. They also change a lot of the dialogue around Leo and Toby's fight in the Pines about what they mean to each other and where Toby admits more about his past. I think the purpose of this is to soften Toby a bit and not make Leo just a sex object to him. I'm still running it through my brain and can't decide if I don't like it as much or if I was just thrown by the change. They also have Leo find out how much he looks like Adam much earlier and not just startled by it at the opening of "Loved Boy." Lopez also rewrote most of the opening night of the play having Toby arrive late and leave early causing a scene. They also cut Eric's voicemails trying to connect with Toby and invite him to the wedding and have him invite Toby during the scene where they meet and tells him he's getting married.
They also cut Toby immediately saying "Adam?!" the second he sees Leo at Walter's house at the end. He says something like "Leo? I never thought I'd see you again" with Leo immediately hugging him for dear life before punching him, walking off to get the water glass to smash on his head. I do. not. like. this. change. To me, that moment of mistaking him for Adam was so emotionally powerful because he somehow just hurt Leo even more than he ever had in that one moment. I felt Sam Levine's soul and heart escape his body in that moment and his rage and pain and sadness were all just so justified that now I just didn't feel. They seem to be trying to soften Toby's edges but at the sake of Leo, who I also found to be the emotional core of Part 2.