There are some big differences between VGcharts totals and Nintendo totals for some of the old games which are not selling anymore. So the difference shouldn't exist.
For exemple:
VGchartz has Super Smash bros brawl has 11.70 millions and Mario Galaxy has 11.84 millions, with a 0.9 million sale advantage for SSBB.
But Nintendo, as of 31 March 2013, has Mario Galaxy at 11.72 millions and SSBB at 11.49 millions, a 0.25 million lead for Mario Galaxy, who is undertracked by nearly a million and sold better than SSBB. But according to VGchartz, SSBB sold quite better when this isn't the case.
It's notable because now SMG is almost even with SM64 as the best seller Mario 3D.
There are other games with a notable difference:
Mario Kart Wii, undertracked by 500k
NSMB Wii undertracked by nearly 1 million
For DS:
NSMB, undertracked by more than 1 million
Mario Kart DS, undertracked by 800k
Nintendogs, overtracked by 500k
Brain training overtracked by 1 million
And the Pokemon:
Soul/Silver remake undertracked by more than 1 million
Pokemon Black and White undertracked by 700k, who are at 15.4 millions and not 14.7.
There is also a notable error with Pokemon B&W, with the European and rest of world numbers obviously inversed.
