Single payer actually refers to it being one single body that pays for the healthcare. Its universal healthcare as in all our taxes go to a fund to pay for everything.
Im actually still not fully sure how Obamacare changed the structure but our system now is where healthcare is paid from a mix of public and private bodys. I think Obamacare added a basic fund that everyone could use?
the tl;dr part of it:
the american health care system basically has five major components
- employer-provided, private health insurance
- individual/family, private health insurance
- Medicare, public health insurance (65+ and disabilities)
- Medicaid, public health insurance (the poor, various stringent eligibility requirements) (e: this is referring to how it was prior to the ACA's expansion)
- Tricare/MHS, public health insurance (military & DoD)
the ACA expanded Medicaid (in participating states) to 138% of the federal poverty line, which gave roughly 15 million more people insurance
it also established exchanges on which private health insurance providers could sell individual policies, which account for the rest of the expansion of insurance