I don't quite follow you.
Styles often include extensions to kde which must be made integral to it's operation.
As a result some degree of compilation is often (but not always) needed. In turn Styles are usually supplied with an installer script to handle this for you.
Themes (which seem to be less and less supported) were supposed to incorporate styles, colors, backgrounds, icon sets, etc. but their installation could not handle the above specifics of styles.
As a result Desktop Themes seem to have fallen out of favor in that there seem to be less and less available.
Conversely styles, backgrounds, and icon themes now abound.