Both services are broadcast in real time, but some channels on both
services are voice tracked. In XM's case, the most popular channels
are live while others are voice tracked. As a listener, you can't tell
the difference as they are careful that no hints are given out when
voice tracking occurs. You cannot hear old programs within having
recorded them (one of XM's receivers can automatically record programs
for later playback similar to the way a TIVO does).

I think both services provide a program guide. I know XM does; and I
seem to recall Sirius does (or did).

They made a better looking Satellite radio by Tivoli. I do not
like
those very tech looking satellite radio that looks like a walkman. I
find them very cheap and confussing looking.

Both services have table radios. Sirius has the Tivoli:

http://www.tivoliaudio.com/product.p...175&cat=&page=

XM has several models from Eton, here's one:

http://www.universal-radio.com/catal...le/e1xmlrg.jpg

Because XM has a technology lead, "XM Ready" radios are starting to
show up in large numbers. Over the course of the next 12 months you
can expect just about every radio-related device to show up with an "XM
Ready" version, where you just plug in the antenna (which costs less
than $50) and go. XM has come up with a chip that manufacturers can
use to convert almost any device to an XM Ready radio for almost
nothing. If you're sitting on the fence, you may even want to wait a
few months.

In AM/FM/XM radios, the XM signal comes from the satellite, the AM/FM
come from plain-old AM/FM transmitters. AM/FM broadcasts will still be
as bad as they always were.

XM has the better content all the way around (IMO), but Sirius has the
Tivoli which sounds more to your liking.