Package/Case Values

What is the different between Package and Case? Is it the same thing. I found a list of values for Package/Case (capacitor)

01005

0201

0204 0306 0402

1.5mm x 1.7mm

10.2mm x 10mm

10.3mm x 10.3mm x 10.0mm

11.0mm x 10.3mm x 10.0mm 11.9mm x 3.7mm x 3.9mm 13.0mm x 13.0mm x 12.5mm 14.5mm x 6.3mm x 7.05mm

Axial Chassis Mount Disc - Radial High Post Screw Threads Q Case Radial Screw Mount Snap In SQ Case S-Type SVT TUMT6

How come they have different format? Can 1.5mm x 1.7mm translate to 4 digits code? What is the meaning of Axial, Q Case, SQ Case.... TUMT6 ? Is there anywhere I can find the info on that? And are those the same thing as, lets say, 0201? Or are they "Mounting Type"? Why sometime we have 3 (2mm x 3mm x 4mm) dimension and sometime only 2 (2mm x 4mm)?

Thanks