The difference between digital and optical zoom has not been referred to a whole lot but in case you run into it, here is the main difference between the two. Both allow you to zoom to a specific target, but an optical zoom is the more traditional version. Honestly, it is the version you probably depict when you think about zooming. It uses the lens’s optical glass to magnify the image. A digital zoom, on the flipside, is basically the same concept except that it is digital and blows up the pixels using interpolation.
With both, the more you zoom in the more you blow up the pixels and as such, the quality will begin to diminish.