Korean harem manhwa often features multiple female characters vying for the attention of the male lead. The art style is usually colorful and detailed.
Common traits of harem manhwa smut include a male protagonist surrounded by several interested females and a lot of sensual and adult-oriented content. The plots can sometimes be light on story but heavy on the romance and intimate moments.
Common themes could include forbidden love, family secrets, and power struggles within the harem. Tropes might involve rivals for the protagonist's affections and hidden agendas among the siblings. Also, there's often a lot of emotional turmoil and character growth.
The main distinction of porn with a story genre from regular porn is the presence of a coherent narrative. Regular porn often jumps straight to the sexual action, while the story genre tries to add some kind of story framework around it. But in the end, both are adult-oriented and feature explicit sexual content.
Well, it's hard to say for sure. The concept of 'porn-like' is quite subjective. Some might consider certain novels with excessive sexual descriptions as such, but it depends on individual perspectives and cultural standards.