personally i think the whole art known as "Machinima" is just questionable really.
especially as the meaning has changed around 10x in the past decade... Machinima 10years ago was a process in which you used to create movie animations using effects which could be translated and blended into the gameplay. (FFXI movies a good example)
then it became a case of skeletal animation scripted features and ingame cutscenes...
now its just... oh forget it i give up on whatever the hell they wanna call it.
7th Day Project was originally a Game Engine based Movie (technically the description of Machinima you've just given) ... however it was dubbed a RTCG (RealTime Computer Generated) Movie.
the only difference between my RealTime engine which became known as Luma and the LumaRender Engine is that one uses realtime tricks and effects, whereas the other uses the processor&gpu to be non specific allowing it to work on ALL systems but slower.
There is no difference between scripting it for the realtime engine or for the render engine ... they both produce almost identical results which can be tweaked.
The only REAL difference is the Luma Engine requires specific hardware and alot of power to run ... the Luma Render Engine does not, it'll export to any system (and on any system) to be viewed back in a video format of compilation.
personally i think all the term of Machinima is really a pure waste of time and effort.