There's a Difference Between XM and Sirius?

An interesting thread developed at my favorite "deals" website, FatWallet.com, regarding an alleged hot deal on a Sirius receiver.

What's interesting is the debate that fired up over the merits of Sirius as opposed to XM. Looks like both companies have dedicated fan bases. I guess I shouldn't be surprised by this, but I was. We terrestrial radio-heads tend to consider satellite radio as this monolithic entity, but they're clearly not.

Then, I found an article in the Washington Post. I guess I'm not the only one who had trouble telling them apart if the Post thought it was necessary to explain it.

So, for now, both companies are probably more focused on competing against each other than against terrestrial radio. When those two companies someday merge, however...