Old "Analog" camera that used film did only use optical zoom, shifting of the point of focus by changing the length between lenses. The first generation of digital camera's used a very simply trick, simply lower the number of pixels like: one use one skip one use one skip etc.. this made the image two times larger but the file size the same thus like zooming in 2 times !!!.. This is nice but your picture resolution is going down and down if you zoom in 5 or more times.
Better is optical zoom since this will make the projection on the optical sensor larger and thus keeping the resolution the same, problem with this is that lenses need to be very good without defects in the glass etc..
So best is Optical zoom and the fewer the digital zoom, pixels: More does not always mean better, better look at all options and price too. now 8 or 10 M pixels with 10 times optical zoom is perfect for normal people...