Chaste
No sex, much like Traditional Regency, with only a hint of kissing.

Titillating
A hint of sex, but no love scene.

Sensual
A vague description of a love scene, but does not include details.

Hot
Most romances fall in this category. Very descriptive with words like: "cock", "shaft", "erection", etc.

Erotic
Warning — books which are rated erotic contain one or more of the following: explicitly detailed love scenes, explicit language, non-traditional sexual positions, multiple partners, mild bondage, etc., and are not for the faint of heart.