The optical microscope is the most common. It uses light to image a sample that is too small to be seen by the naked eye.
The scanning electron microscope examines the surface of objects using an electron beam and measuring reflection.
Short Answer = Resolution.
When viewed through a microscope, things appear to move in the opposite direction than they are really moving. If you move an object to the right, it appears to move left. The lenses of the microscope reverse the image.
*A microscope magnifies because if it enlarged an object, it would make the object under the microscope physically bigger.
*Magnifying just makes it appear bigger than it actually is.