The obvious difference between a domestic cat and a tiger is one of size, but if you keep the latter as a pet you might notice a qualitative difference around other pets and small children.
But I'm not sure we should be cheering the move from Microsoft's distributed desktop stronghold to Google's centralized server farm. Certainly I think there's a role for big searchable stores, but this particular case could herald a monopoly just as dangerous as MS's.
Always remember that the purpose of any company, and the duty of its officers, is to maximise shareholder value. My observation is that the larger a company grows, the more it loses touch with its founders' core values. Gradually all companies converge and become indistinguishable their core values. I think this is inevitable. At some point each company will want to be the best xyz in the world, but to be the best xyz means crushing the opposition who are also trying to be the best xyz and they're playing mean. Microsoft was once a cool startup that fought against the hegemony of IBM. Now the roles are reversed and the Internet community cheers when IBM wins one over on Microsoft. In twenty years time I guarantee that those same people will be cheering Microsoft on each time it wins a battle for the individual against Google's data stranglehold.