Broadband, is just a generic term for a fast internet connection. I would describe your cable connection as a broadband connection. It used to be that broadband mean't 512k download speeds, but it seems these days that, 156k download speed can be described as broadband..
Anyway onto ADSL..
ADSL is Asymmetric Digital Subscriber Line.. Asymetric because usually, the download speed is faster than the upload speed. the upload speed is usually half the download speed.
Some ISP's are now offering SDSL.. which is Symmetric Digital Subscriber Line.. which offers equal up and download speed.
As for setting up a home network, if you're using a crossover cable, and just using Internet Connection Sharing, then there will be no difference between the two. just Share an ADSL connection like you share your cable connection.
Hope that helps..