What's the difference between "Comcast'' and "Microsoft.''... What exactly are they?

You can Google for the difference and there can be a number of interesting answers out there!

Comcast is a cable telvision service that provide cable TV channels, Internet access and VoIP services. Microsoft is primarily a computer software company (though they do sell hardware like XBox, mice, keyboards). The two have absolutely nothing in common except for the fact that Microsoft would like to control the cable industry too.