The only difference between a community cloud and a public cloud is that a community cloud is built for a specific community and verifies customers are part of that community. This provides security and ongoing compliance.
With Vault's Government Cloud you can be sure that the only people using the infrastructure you are using are government employees or cleared and authorised contractors. This is a layer security that public cloud providers don't provide. There have been breaches of government data using by attackers getting on a public cloud and attacking other users through the infrastructure.
Vault's Critical Infrastructure Cloud is built to the same standards as our Government Cloud and provides the same guarantee for critical infrastructure providers. This allows Critical Infrastructure providers who face the same threats as government to adopt the same security posture, with the click of a button.
Two factor authentication
A physical authentication device can't be hacked like a software token on a smart phone. This makes sure only verified users, whose government issued photo ID and clearance number have been checked, are on the Government Cloud. Likewise, it ensures that users of the Critical Infrastructure Cloud are who they say they are, based on their government issued photo ID, and belong to those industries.
Who's on public cloud?
Nobody really knows, most public clouds let anyone in the world with a credit card sign up. Hackers who do this can then start poking around the "attack surface" inside a cloud, looking for a flaw in a hypervisor or storage system so they can steal data from other users of that cloud. This has happened enough times it has a name: a "cloud hopper attack".