Sorry for the wait!!
Form factor is the biggest difference when it comes to part numbers.Many SSD's are for for laptop's.
The R5's are 9.5mm good for desktops.Those with a "J" are 7.0mm and designed for laptop brands.The "M' stands for multi-level cell.
I'm guessing the smaller the form factor the more expensive the production......
The link above does not seem to be working, but I believe Infocus is referring to the height of the drive.
There are two different possible heights (7 mm and 9.5 mm) that are available for the 2.5 inch form factor.
Here is a link to the X-25M G2 datasheet where both are outlined:
Unfortunately, the datasheet does not match up form factor with model numbers.
The reference states 'better and faster' but the specs. given haven't changed. Is Intel this difficult to get information from about the rest of their product lines?? I have a couple of G2'-Ms (one is in the process of being replaced currently), two V's and an OCZ drive ( Vertex 2 ) - the people at OCZ are much more responsive to questions and issues.
The only thing to be concerned about is weather or not you have the very latest firmware!
G Mac's SSD should be up to date where firmware is concerned,he has a fairly new drive!
If your wondering weather yours is up to date look at the White Sticker on your SSD,look for FW: 02HD ....
Thats it! 02HD is the latest Intel firmware.Don't let Newegg's marketing strategy get to you ....