The telescopes that uses lenses instead of mirrors to gather light are called as Refractor Telescopes. They produce high-contrast images with sharp and crisp views of the astronomical objects like moon, planets, stars, galaxies and nebula. Refractors are known for their rugged simplicity. They are very easy to aim at, need less of a maintenance and once the lenses are aligned they rarely need it again. They are equally popular amongst beginners of astronomy as a hobby and armature star gazers.
Reflectors are telescopes that use mirrors. They most commonly use a main concave mirror at the bottom of the tube, which focuses light back up to the top of the tube. There, a small flat mirror placed at right angel, reflects the light to an eyepiece placed on the side of the telescope body. Reflectors telescopes offer larger aperture for the money you spend than refractors and providing enough light to see moon, planets and hundreds of deep-sky astronomical objects. As the mirrors in reflector telescopes not covered due to the design, they are expose to dust and grime which may need occasional cleaning and adjustments to keep them properly aligned.