ARM LPC 311 vs 401 vs 501, what does it mean?

[zapta]

I am looking at page 3 of the datasheet here :

http://www.nxp.com/documents/data_sheet/LPC11U3X.pdf

The same product has suffixes like 311, 401, 501, and when setting a project in the lpcxpresso it asks for the exact suffix. 

What do these number mean? Are they NXP specific or more general for ARMs?  Does the compiler generate different code based on the suffix?

[ElektroQuark]

Not same product. See Table 2. Different amount of FLASH, RAM, etc...

[Jeroen3]

Microcontrollers begin with LPC, then add the base family LPC11.
Follow with a application specification (such as usb, or low power) LPC11U, then the two numbers will tell you something about the peripherals inside, but they should all be binary and pin-compatible. You get LPC11U37.
The appended letters specify the package (including tempature for some families), and the pincount.
After the slash is the revision identifier, or al least that is what it looks like. The LPC11xx's have a lot of those. (not to confuse with the revision designator you find on the package and errate sheets)
But, on the LPC17's these numbers are missing.

Company's often use the strangest numbering scheme. Possibly due to the many continents they're based at.