Doubt comparing zonestat and swap -s figures?

Can you, please, help me understand why the highlighted figures differ and relate?

root@vlab-3:~# zonestat 1 1
Collecting data for first interval...
Interval: 1, Duration: 0:00:01
SUMMARY                 Cpus/Online: 24/24   PhysMem: 23.9G  VirtMem: 27.9G
                    ---CPU----  --PhysMem-- --VirtMem-- --PhysNet--
               ZONE  USED %PART  USED %USED  USED %USED PBYTE %PUSE
            [total]  0.41 1.71% 9759M 39.7% 10.1G 36.1%  335K 0.01%
           [system]  0.41 1.71% 9680M 39.4%  9.9G 35.6%     -     -
             vlab-3  0.00 0.00% 79.2M 0.32%  126M 0.44%   228 0.00%


root@vlab-3:~# swap -lh; swap -sh
swapfile             dev    swaplo   blocks     free
/dev/swap             -         4K     4.0G     3.9G
total: 472M allocated + 197M reserved = 668M used, 18G available

Would that mean that 27.9G - 18G = 9.9G of virtual memory are used?
But where withing [system] that I can't see (understand) it?