'Direct field" and "near field" mean exactly the same thing, just that the term "nearfield" is actually trade-marked, so the generic term "direct field" came into play.
Reference monitor means different things at different times -- iit's mostly a marketing hype term.... just like the word "professional".
Nearfield monitors are intended for listening distances of several feet (that's 3-4 or so), mid-field monitors are designed for distances further than taht and are generally used in larger control rooms.