So here's what I've learned are what certain packaging formats are called:
-Jewel Case - pretty obvious, been a standard for decades since the original CDs were introduced. These can house 1 or 2, sometimes 3 CDs or various Discs (SACD, DVD-A, DVD, BD, etc).
-Super Jewel Case - these are like the above, but have rounded corners. Not sure why there was a distinction made, but for some, they look nicer.
-Digipak - These have become a new standard in reducing plastic for CD packages. They can come in two or three panel fold-out paks, usually have a pocket or a die-cut slot to hold the liner notes booklet. They may also have plastic trays glued inside of them to hold discs, or the discs may slot into pockets, onto nubs inside the disc hole, or sit inside die-cut slots.
-Digibook - Like the above, but the liner notes booklet is glued into the case, making it unable to be removed, giving it a book-style feel, thus the name.
-Mediabook - Like digibooks, with the booklet glued into the packaging, but these are usually a bit bigger than normal CD cases, and feature a hardcover-book-style outside, and typically have plastic trays glued to the inside of the front and back covers to hold discs.
-Artbook/Earbook - as stated above, these are much larger than mediabooks, usually vinyl/LP size albums and so they feature larger pages for the booklet/liner notes, usually with extra art or text from the band or others.
Note - I've seen both digibook and mediabook used interchangebly so it can be confusing, but basically both are just disc packages with the booklets bound into the spine of the package. They may or may not feature hardcover style front and back covers, but the distinction is usually the booklet being set into the package, just like their bigger artbook relatives.
Did I miss any? It's weird how many ways CDs have come to be packaged over the years, and they're all usually to necessitate the inclusion of extras, be is an Instrumental Version of the album, a DVD/BD audio version with surround sound and/or behind the scenes video, bonus discs with exclusive tracks, or all of the above. Of course, they also cost a lot more. Most mediabooks run $25-35 depending on the band, label, and what's included, though some have gone cheaper. Artbooks tend to go for at least $50 and sometimes as high as $150 depending on what's included (looking at you, Steven Wilson...).
Artbooks are the general term used by record companies to refer to larger-sized albums, usually 12"x12". Imagine a mediabook album but larger. These typically house more than two discs, and sometimes up to eight (four on the inside of each cover). They are also sometimes referred to as "earbooks".
So...wait...I don't know what a "mediabook" is either. Are you talking about the liner notes and what-not that come with a vinyl record (the 12x12 reference)? The links you gave just showed multi-disc CD packages, but that doesn't seem to be what the OP is talking about.
As far as I can tell, the ones I linked to ARE what the OP is talking about. Those are the four currently available/released Dream Theater artbook releases. They're just called that because they're larger albums that allow more pages to be included, thus more artwork.
-Marc.