The US classifies non-citizens based upon the avenue of entry into the US.
Yes, it is clear that this service is available for non-US citizens.
Treated differently in what regard? Many US citizens would argue that, in some respects, non-citizens are even more privileged than they are. In many cases the only privilege that a non-US-citizen doesn't enjoy is the right to vote in a US election.
Yes, non-US citizens can buy I bonds as long as they meet the eligibility requirements set by the US Treasury Department.
No both citizens and non citizens are protected
Yes, non-US citizens can use Clear for expedited airport security screening.
All people visiting Alpha Centauri. Non-U.S. citizens
To most US citizens it is. To many non-US people it is not
no
Check the related link. As of Jan 2007... Legal non-Citizen Residents: 18,870,000 Illegal non-Citizens Residents: 11,780,000
Yes, non-US citizens can apply for TSA PreCheck to expedite their airport security screening process.
Yes, non-US citizens can travel to Cuba. The requirements for them to do so typically include a valid passport, a tourist visa, and compliance with Cuban entry regulations. It is important for non-US citizens to check with their own country's government for specific travel guidelines and restrictions to Cuba.
None. You must be a US citizen to get welfare benefits.