There are many similarities, but the nature of the products each produces introduces some differences. Valve creates occasional monolithic products that depend heavily on art direction and experience design. Google produces a complex, interconnected system where Everything Must Scale.

In some ways, Valve manages to be more extreme, because it's smaller. 250 employees could conceivably be totally flat, if they are all committed and the boss is ... brilliant.

Google has a few more employees.

The idea that everything is shared, and people do pretty much whatever they want is nice, but doesn't work if you want as many heads as Google has.