SACD -- Hybrid, Single layer, Stereo, Multi?

Is there a qualitative difference between Hybrid,
Single layer, and pure DSD SACD's?

Can a single layer multi-channel SACD also play in Stereo

Can somebody give me a rundown on this?
If by your question you mean ... can I pop a multichannel SACD into my SACD player and play it through my 2 channel system and my SACD player will recognize the SACD layer(s) of the disc and play the SACD ... the answer is "yes." You will just hear "SACD sound" from 2 speakers. Logically, this is not different than playing a DVD video through a DVD player connected to a 2 channel stereo system.

Try this site for more detailed information about the different types of layers possible on a SACD ...
Rar1 --

Thanks for the link. What I am wondering is -- whether
or not a Stereo SACD usually includes a multi-channel
SACD version and whether a multi-channel SACD usually
includes a Stereo SACD version -- AND -- if there is
a qualitative difference between the play-back of a hybrid disc and a pure DSD disc.

Mostly, I would like a definition of these terms so I
have some idea what I am getting when I buy a SACD, but
I also want to know if having a regular CD layer in any
way reduces the quality of a SACD.

1. All SACDs have a stereo SACD track.
2. Multichannel SACDs add a multichannel track to the SACD stereo track.
3. Hybrid SACDs add a CD (redbook) layer to the SACD stereo track.
4. Hybrid multichannel SACDs add both to the SACD stereo track.

The quality of the SACD tracks on hybrid SACDs is not any different from that on non-hybrids.
The stereo SACD track is mandatory and resides on the SACD player. This is the bare minimum. You can also optionally a have a multichannel mix to the SACD layer, but this is not required. Any multichannel SACD disc will have a stereo mix. you can also optionally have a redbook CD layer (hybrid) in addition to the CD layer. Either of these two options are independent of each other.
Kr4 and Aroc -- Thanks for the info!
So basically, there are no sacds that are STRICTLY MULTICHANNEL? I've always wondered this as some of the labels on the outside will say "sacd Multi-Channel" which confuses me on this issue. I've always thought these particular discs were only multichannel and would sound terrible on my stereo setup. Am I misinformed here?
There are NO only MCH SACDs. All SACDs have a stereo track.