I am new to 3D printing and am finding I may have to severely edit my designs which may be too optimistic for the printer's capabilities. I have been studying various printers specs and am confused by the resolution (typically Z axis) that has a wide range listed. For example, the ultimaker 2 has a layer resolution listed of 200 to 20 microns. What does that mean?

Is that the min/max that nozzle will be able to print and varies depending on how you select the finish of the object when sending it to the printer? Or does it vary by material being used--one material you can get expect a nice finish at 20 microns, but another will be chunkier at 175-200 microns? Or is it a total crap shoot and the expected performance of the printer could be anywhere from 20-200 depending on which way the wind blows, relative humidity, and alignment of planets?

Any insights appreciated.