Why does GPUz report different video game usage stats for GTX 780's vs. 6970's?

When I used to monitor video game usage stats using GPUz
for my old 6970 there were always two stats reported:

memory usage (dedicated)
memory usage (dynamic)

where the dedicated memory usage was usually
greater than the dynamic (except in Call of
Pripyat).

but w/my GTX 780 it only reports:

memory used

I had always thought that the dedicated memory usage
referred to the 6970's on-board VRAM while the dynamic
referred to system memory allocated for the 6970 (like
DIME?), although maybe I'm wrong about this.

Because they're different GPU's from different generations made by different manufacturers on a vastly different architecture.