What is the basic difference between the two types of optical telescopes?

Answer 1

Actually, there are at least three types. Refractor: A series of lenses, the classic "spy glass" style, carried to the extreme. Then there is the Reflector: Invented by Isaac newton, uses a large mirror ground to a parabolic curve, and focused at the eyepiece. Lastly there is the various designs of catadioptric telescope, the most common being called the "Schmidt-Cassegrain". They use a series of different mirrors and an eyepiece to try and strike the balance between refractors (small field, large image, but dull and fuzzy), and reflectors (large field, small image, but sharp and clear). They give excellent results, but are far and away the most expensive type for the amateur. The mounting of a telescope is almost as important as the type. Simplest, most common, and least expensive is the alt-azimuth mount, but it has a half-dozen built-in frustrations. The equatorial mount is fussier to set up, requires more "homework" to use, but is much more satisfying in the long run.

Answer 2

Refracting telescopes use lenses to collect and focus light, while reflecting telescopes use mirrors. Reflecting telescopes are generally better at reducing chromatic aberration, which causes colors to blur in refracting telescopes. Reflecting telescopes are also typically more compact for their aperture size compared to refracting telescopes.