Physical meaning behind is similar: resolution - the capability of an optical system to distinguish, find, or record details / resolving power - capacity of an instrument to resolve two points which are close together (it can be angular, spectral etc.). 

Dear Abbas,

Resolving power may be defined for any spectrometer, spectorscope (or actually measuring device measuring some quantity R) as R/Delta R. The denominator (Delta R) is the smallest difference that can be distinguished, i.e. the resolution. Thus one has resolving power as the inverse of the resolution. This is nice: a small resolution translates into a high resolving power. However, one should note a oddity here: Resolution (and I assume you mean e.g. spatial resolution) is often defined as the smallest distance which can be distiguished. Given that "to resolve" and "to distinguish/separate/..." are synonyms, this does not define anything! As pointed out by many, resolution is not a well defined physical quantity. It is rather an ability (or a power...). I guess this is why people talk so much about "resolution criteria" and less often about its definition,

best regards,

Oliver

The term resolution is always relevant to the separation of ions of two different m/z values (∆m) such as 1 m/z unit will have the same separation at m/z 100 and 101 as they do at m/z 2000 and 2001.

The term resolving power is defined as the difference in m/z values of ions that can be separated from one another (∆m) divided into a specific m/z value (M) (i.e., R=M/ ∆m), the values for R would be 100, (R=100/1) at m/z 100 and 2000 (R=2000/1) at m/z 2000.