This seems to explain things pretty clearly.

Definition Task Manager Process Explorer vadump -s
Physical memory in use Mem Usage Working Set

Private (no DLL) VM allocated/committed VM Size Private Bytes PagefileUsage
Total VM (including mmap, dll, etc) N/A Virtual Size (Image + Priv + Mapped) Commitment + Dynamic Reserved Memory

On 32-bit Windows, max address space (virtual size) is 2GB.

The 3 types of commitment in vadump -s are:

  • Image: process executable code
  • Mapped: memory mapped stuff like files
  • Private: process heap (and stack?)

vadump -so has a section that breaks down working set. Two entries are important: Heap is Windows native heap, and Other Data would be, e.g. CLR and JVM stuff.