There’s a different pace to YA fiction. The books shorter, leading the feeling of accomplishment you get when you finish the book, and the story moves at a different pace. The plot is more central to the story, too.
In adult fiction, so much energy is taken up with complicated emotions and motives. When its well done, its really well done and worth the time and effort, but YA fiction has little of that. The emotions are just as real, but the twists and turns are less complicated, more straight forward. It’s a nice sitcom break from hour long dramas.