What's the difference between a microcoil and an 'open' coil?

[Souterain]

I see the different coils people build, and just wondered what the difference actually is.
My coils generally have about 0.1mm gap between the windings and work fine. I have also used microcoils of various diameters (I assume they're microcoils, anyway, as I heat and compress the windings together).
So making the coils isn't the problem in the first place, I'm just wondering which is actually better to use.
Is one type better for, say, higher resistance and another for sub-ohm builds? I haven't yet found any definitive answers. Possibly it's a case of horses for courses, much like PC vs Mac, PS3 vs XB360 or Star Trek vs Blake's 7.

 

[sparkyjuice]

Micro coils are traditionally 2mm dia, more commonly coils touching together.
I used these frequently as they are robust and easy to rewick
I am now switching to open coil ribbon and voodoowool builds on mechs as they give me personally more flavour.