What is the difference between these two lenses? - 1

Can you tell the difference between Nikkor AF 50mm f/1.8 D and Nikkor AF-S 50mm f/1.8G what does D and G stand for?

The most significant difference is AF and AF-S.

An AF lens does not have an internal focus motor, and requires the camera itself to have the motor. Entry level cameras such as the D3xxx and D5xxx series do not have autofocus motors, so they can't autofocus "AF" lenses.

AI-S lenses have autofocus motors built into them so they will autofocus on any camera.

D lenses have an adjustable aperture ring, while G lenses do not. But with today's modern cameras, you really do not need the aperture ring as it is adjusted by controls on the camera. D lenses (those with the aperture ring) are mostly or backwards compatibility for older Nikon film cameras.

To add to the first answer…

A Nikon D lens tells the camera body the distance at which it is focused, the camera body then uses this information when setting flash exposure with a D-TTL or iTTL flash, depending on which body you have.

A Nikon G lens includes the D function, but has no aperture ring.

Nikon built the 50mm AF-S so that users of the bodies without a focus motor could use a fast 50mm that would actually auto focus on their cameras.