DSL is like an upgraded phone line. One benefit of DSL is that it is regulated or something, and your phone company has to allow competitors to open up their own ISP at the switching station / office. DSL usually is cheaper because of this competition, although at times the phone company can drown some DSL providers by charging a lot for use of DSL lines to the ISP...

Cable internet service is provided by your cable company. No competition, at least not that I've heard of recently. If an ISP wants to operate on cable, they have to work a deal with the cable company. This is because the classifaction is broadcast (ie cable TV is one way) while phone is classified telecommunications (you call people and get calls). Until this is changed, nobody can have competition on cable unless you can switch providers...


The allocation of bandwidth is different also. Cable has a single fiber line that transmits both TV and maybe one or two channels of cable internet. The more TV channels, fewer internet channels. This single fiber goes to pretty much everyone on your block, or anyone connected to that green box. There it is converted to the cable TV connection for TV, pay-per-view, internet, etc. And everyone shares the internet channel, and the fewer there are, and more crowded....well adiz summed that up nicely.

DSL is your normal phone line, but operates outside of the regular phone frequencies. This lets you use your phone for phone calls without interrupting your internet connetion. Since it takes a higher quality wire to keep this signal strong, if you have bad telephone wires DSL won't be quite as fast as it should be. Usually a DSL signal is pretty good for a few miles outside of the switching station / central office. The closer you are, the stronger the signal and faster your internet.


Now I'll talk about the connection I miss so much... My 12mbit dl and 1mbit up connection in Japan. They already offer a 40mbit service downstream with 1mbit upstream, and 24mbit down streams are pretty cheap. I think I got a free DSL modem with wireless AP built in for $20-$40 a month with 3 free months during the campaign for Yahoo! BB... Such a sweet connection, and all on two wires. Yes, I had a cheap phone line with only a single twisted pair, providing 12mbits... Technology at it's greatest... *sigh* Now I'm in Idaho and got Wireless since it isn't much more expensive than DSL ($50 month here ) and I can get about 4mbit up/down since I'm on a rarely used antenna and like 100m away from the ISP's building with their connection... Better than the same amount for 768/486 IMHO....except I had $500 in equipment to get...and that fact that they don't even offer DSL to my place...

Hope that is clear/understandable, and shows how badly people in the US are getting screwed for bandwidth on DSL...