Hello Amber

From my experience.....there is little.
I think it has something to do with subcontracted providers.
I use road-runner...which is a cable connection.....however my service and money goes to Time-Warner Austin "The Cable Company".
My boss uses earthlink like you do.....and has dsl.....but his service is provided by, plus his money goes to Southwestern Bell.
and he has a contract.
When it gets in to the nitty-gritty of details it comes down to how the information is getting to you....meaning cable or telephone wires.
The company who owns the wires set the details.
Earthlink nor Road-Runner own the wires they just rent the bandwidth....kinda like renting an apartment.
I like my cable modem service and I have no contract and was issued a I.P. address.
I find that my bosses dsl is slower and he is not issued an I.P. address but used PPoe.
I understand how to Finagle and I.P. address so that multiple computers can access the internet on that one I.P. so I am not charged extra.
I know nothing about PPOe.
My vote is that you go with the cable modem.
I am sure Adolph has more info but
would probrably agree.