Why is an SLR camera better than the automatic?

SLR or single lens reflex refers to a particular type of camera in which the image and the viewfinder are both taken from one lens. effectively WYSIWYG.

auto focus auto exposure modes have been available in SLR cameras for a very long time thus making them "automatic."

As a side note an SLR need not have exchangeable lenses to be an SLR nor are all cameras with exchangeable lenses SLR's.

The primary advantage of SLR's is the fact that the image in the viewfinder is pretty much the image that you get when you release the shutter.