Thank you to all who have weighed in on this subject - Mary and rlduval.

Good information for all to be aware of.
I have been in contact with someone who is very knowledgable about Disney admissions. They reminded me that Disney is VERY good at protecting itself and would never allow ticket wholesellers to sell tickets that were not "for sale" to everyone.
Now, the difference lies in how these "different" tickets are advertised. Disney does restrict the ADVERTISEMENT of the "odd" tickets that we read about - 5 day/ 4 plus hoppers, 3 day hoppers, FITS, etc. All of these tickets are not advertised on any websites, but may be made available to people through various mailing lists (ie: Mousesaver's Newsletter) and by calling the companies and asking about "other" tickets.
The link that I provided above is not available DIRECTLY on the DiscountOrlandoVacation website. I found it by doing a search for 3 day hoppers on the site. When you click on the link, you read this:
These are specials that we do not advertise in our shopping cart. These are reserved for newsletter subscribers and members of theme park message boards.
So there is your difference.

These special tickets are not ADVERTISED to the public. But they may be BOUGHT by the public!
I would not hesitate to purchase ANY of the tickets that are offered for sale by any REPUTABLE Disney reseller. To find out if a company is reputable, do your homework - check with the BBB, do a search on these boards, etc.
I know that I feel better about these tickets. I hope that the rest of you do too!
