Well, a oneshot manga is like a single, self-contained tale. It doesn't continue in subsequent chapters. Sometimes, it can introduce new concepts or characters, but it wraps up everything in that one issue.
Straight smut manga often features explicit and adult-oriented content, focusing on romantic or sexual encounters without much emphasis on complex storylines.
A mature-looking girl in such manga often has a composed demeanor, shows confidence in her actions and decisions, and has a certain wisdom beyond her years.
Well, smut manga typically features a lot of sexual imagery and scenarios. Regular manga, on the other hand, can be about anything from superheroes to school life and doesn't focus mainly on sexual themes. The main difference is the emphasis on sexuality in smut manga.
There aren't many common elements. Manga is a broad form of comics, while smut usually refers to explicit or inappropriate content. They are quite different.
Smut is kind of raunchy. Yaoi is for those interested in male-male love stories. Manga is just a wide range of comics from Japan that can be of any type. So, they're quite distinct from each other.