Refractors use lenses to gather light from dim objects while reflectors use a mirror. Refractors are the long narrow tubes with the eyepiece at the back end. Reflectors are usually shorter, fatter and open at the top. In most styles of reflector, the eyepiece is placed near the top. Refractors provide good, sharp images and are good for observing pinpoint light sources such as stars and planets, but tend to be on the expensive side.
Reflectors are good for observing more diffuse light sources such as galaxies and starclouds.
They also provide good, sharp images but they are much less expensive because reflectors reflect the gathered starlight from just one surface. In many stores telescopes are sold by their power of magnification. The eyepiece magnifies the small image. Different eyepieces have different magnifications. The numbers on the eyepiece refer to their focal length.