Minolta Numbering System: Confusing For a Beginner

I have doing some research on buying a "consumer" SLR. I had pretty
much settled on a Minolta Maxxum 5. However when I look at various
camera shops I often see models referred to a Maxxum 50 QD. Is this
the same a Maxxum 5? What confused me more was that also looked at
buying a Maxxum 70 which appears to be the successor to the Maxxum 5.
However I see on some camera sites models that are referred to a Maxxum
7 and Maxxum 70. It would appear, judging from the price, that the 7
is a different camera from the 70. This makes me wonder if the Maxxum 5
and Maxxum 50 are different cameras I have got myself quite confused
now and haven't even yet decided on a lens! Can someone give clarity
on Minolta's numbering system?

Thanks

Paul "Tinshed" Hellyer