DOCUDRAMA
A docudrama is a type of work (usually a movie or television show) that combines elements of documentary and drama, to some extent showing real events and to some extent using actors performing set pieces to take dramatic liberty with events. A docudrama is usually based on historical events, providing an analysis to past events.
Drama documentary is a relatively new form of drama. It bears many similarities to a mockumentary. However, whereas these tend to be parodies, drama documentaries usually have a more serious standing. They are often used to analyze current events and issues, in a similar way that businesses use scenario planning. A drama documentary is different from a docudrama. A docudrama is usually based on historical events, providing an analysis to past events. Drama documentaries, on the other hand, are based on fictional events, although they are often researched to make sure that the scenario presented is believable. However, the names are often interchangeable.
SOURCES:
http://encyclopedia.thefreedictionary.com/docudrama
Michael Rabiger. Directing the Documentary. 4th Edition. 2004. p. 102
http://en.wikipedia.org/wiki/Drama_Documentary