The USSR was not structured like one massive corporation. Corporation tends to seek profit; while USSR sought survival. Was bad at it, too: built millions of tanks and other military hardware that rusted without any battle, lost the cold war and tanked.
You're talking about purpose, not structure. I'll agree, the USSR's purpose was not profit, because profit does not make sense if you're trying to own everything. The USSR's goals were growth and, as a logical consequence of growth, not shrinking, i.e. survival. It failed, yes. The larger a hierarchy and its concentration of resources, leadership, and power at the pinnacle, the worse it performs. This occurs with corporations in a capitalist system as well, but since it is not a defining feature of such corporations that they must own everything, their existence is more flexible. They can merge, split, be acquired, get sold off, get refinanced, etc. In this way, the capitalists (viz. people who make their living off of property ownership) can preserve their ownership even if their power structures fail.
So the key difference between the USSR and the Liberal states in opposition to it is the notion of property. Under the USSR, all property is state property and under the Liberal states, property is the bourgeois notion of property.
