What's The Diff. Between AF-S (Nikon) EF-S (Canon)?

I Know That The AF-S Let The Camera AutoFocus Like D3100 Deosn't Have Built In Motor. EF-S I Saw Some One Saying (EF-S lenses will physicaly damage Canon's full frame or APS-H cameras if one mounts them on those,). What Does That Mean?

AF-S is Nikon's term for focus motor is located in the lens. The AF lens requires the focus motor to be in the body of the camera.

EF-S is Canon's lens mount system for their APS-C sensor sized DSLRs. Yes, mounting an EF-S lens to a full frame body is not a good idea.

You are correct that Nikon's lower-level models - D3100, D3200, D5100, D5200 - require the AF-S lenses for auto focus.

The Canon EF-S lenses can't be used on a Canon full-frame DSLR such as the 6D, 5D or 1D. Doing so will cause damage to the mirror due to the protrusion of the rear of the lens into the camera body.

However, a Nikon DX format (cropped sensor DSLR - D3100, D3200, D5100, D5200, D90, D7000) lens CAN be used on a Nikon full-frame DSLR such as the D600, D800, D4 and the camera will automatically crop the full-frame sensor to the size of the cropped sensor. You don't get the full benefit of the full-frame sensor but at least, unlike Canon, you can use your DX lenses on a Nikon full-frame DSLR.

AF-S is an autofocus variation for Nikon that installs an internal motor on the lens allowing for faster focusing like AF-I but the motor used is faster, quieter and has the additional feature of allowing manual focus anytime even if the lens is switched to AF. It's more like USM with Canon.

EF-S in Canon is the designation for lenses made specifically for APS-C cameras. The protruding rear element and smaller sensor coverage do not allow the use of this lens model on full-frame cameras. The equivalent designation with Nikon is DX.

You don't have to capitalize each word in your sentence. Grammar rules tel only the first one should be. You do have to capitalize proper nouns however like Nikon and Canon.

Nikon
AF-S --- inbuilt motor in the lens lets autofocus for all camera's in nikon line below d7000 and d90 which do not have a focus motor in the camera body.
AF doesn't have an inbuilt motor in the lens for camera's above d7000 or d90

EF-S lenses are for canon APS -c camera's

yes you can't use them on full frame camera that is one of canon's problem's whereas all af-s lenses can be used on all Nikon bodies