Okay, so I've been chewing on this one for a while because my bookshelf is a weird mix of both. I think the line gets blurry, but for me, literature horror leans hard into the psychological and the atmospheric. It's less about the monster in the closet and more about the dread of opening the door, or the creeping realization that the closet was inside you all along. Shirley Jackson's 'The Haunting of Hill House' is a perfect example—the house is a character, but the real horror is Eleanor's unraveling mind. The prose itself becomes unsettling, with a rhythm that gets under your skin.
Popular horror fiction, on the other hand, often delivers the monster. It's plot-driven, designed to provoke a more immediate, visceral reaction. Think of a really tight Stephen King novel versus something like his son Joe Hill's stuff, which can straddle the line. King himself has written both kinds, honestly. 'It' has literary aspirations with its themes of memory and childhood, but the scares are concrete and graphic. Popular horror satisfies that itch for a clear threat and a narrative payoff, while literary horror might leave you with a lingering, ambiguous unease that's harder to shake.
I don't think one is inherently 'better,' but they serve different moods. After a long day, sometimes I want the catharsis of a slasher in book form. Other times, I'm in for a slower, more insidious kind of scare that makes me question the shadows in my own hallway. The literary kind tends to haunt me longer, but the popular kind is the one I tear through in a single, nerve-wracking sitting.