I think the only difference between the 3 main sources (NDP group, media create and VGC) are their weekly
estimates and VGCchartz's numbers are usually revised afterwards if they get the numbers off (kinda like hitsdailydouble for album sales). So don't put so much into their very early weekly estimates
But the totals sales are pretty much accurate. They pretty much use media create's data (media create only tracks japan though).
exmp1 ,2
and even
forbes rely on them so IDK