Support structures query

I have several parts to print out that may require some support. What is the difference between "full" and "exterior" support structures. I need to print a fan structure for a model gas turbine where the blades are going to be around 45 degrees to the bed. Does any one consider that these could print OK if I just used a raft and some support underneath the blades? I assume that would equate to "exterior" support. I'm using PLA, 0.1mm layer thickness.

what slicer are you using ?

I'm using ReplicatorG at the moment, but I also have Simplify3D loaded but haven't got round to using it. My system does not like Flashprint because HP systems do not like OpenGL compliant software. I need a new system that will cope better with standard files!