Resolution is the ability of a telescope to render detail, while resolving power is a direct function of aperture. The larger a telescope’s aperture, the higher its resolving power and resolution, enabling it to see finer detail.
For a telescope, resolution is often measured as the smallest angle that can be cleanly “split” or resolved between two stars. This number is called the Dawes limit. To determine this limit for a telescope, divide 4.56 by the aperture of the telescope (in inches). For example, the resolving power of an 8 in aperture telescope is 0.6 seconds of arc (4.56 divided by 8 = 0.6).