what's the difference between digital and anolog tv tuner?

I am working in tv field, i don't understand clearly the difference between digital and anolog tuner. when they tune tv promgram, the way are same? thanks!

"Digital & analog questions"

http://www.aba.gov.au/tv/overview/FA...l_analog.shtml

Regards,
IanP

Thanks a lot, IanP! I learn much from your links!