If you are planning to have a photoshoot in the genres of glamour, boudoir or nude photography (sometimes even fashion), it's better to agree on the level of nudity beforehand. Of course this is a spectrum, but if you can pinpoint your comfort zone regarding the amount of clothes you want to wear, it will help communication for the photoshoot.
Fully clothed doesn't necessarily mean you will be covered from head to toe or the kind of clothes you are wearing, but we can summarise it as safe-for-work content. Gym and other sport outfits also fall into this category.
We are venturing into the lewd categories with lingerie, but for many people swimsuit is halfway there. Lingerie can mean a one piece body-dress that covers relatively more or even a two-piece made from see-through material.
Semi-nude can mean topless, or the opposite (Winnie the Pooh style). These pictures need to be censored for most social media platforms and are considered 18+ content. Between semi-nude and nude there is an in-between category, the covered nude. Basically for these pictures the model has to get partially or completely naked in front of the photographer, but the breasts and privates are not shown due to the poses or covered with hands, fabric or other accessories used during the photoshoot.
Nude has two sub-categories, "open" or "closed leg" (Yeah, I don't like those expressions either). Basically most of the time non-porn nudes fall into the closed leg category, this is what you see in magazines like Playboy. Of course open leg doesn't have to be erotic either, there are many examples of artistic nudes that are pushing the limit.