No real difference.
When I was in college, I had no-name health insurance through my pizza job. A stubborn case of bronchitis led to a chest x-ray, led to the discovery of a potentially life-threatening, possibly congenital defect inside my chest. After seeing the pulmonolgist, but before the appointment with the cardiac surgeon, the insurance company denied my claims as a pre-existing condition. They paid for the chest x-ray and the antibiotics, but told me to piss up a flagpole for the specialist and the CAT scan. A few letters from an attorney later, it became clear that regardless of the merits of the case, I was not going to get blood from a stone and being a stupid kid, I gave up.
Nevertheless, I saw the surgeon and made it absolutely clear that I had no coverage and made about $10k/year. He said I would continue to be miserably sick and it would eventually, in months or years, kill me. Assuming that I could eventually make money enough money to pay him if I wasn’t dead, I opted for surgery the day after finals ended. When I scheduled the surgery at the hospital, I again explained my non-covered, penniless situation. They told me I could pay $100/month once I got back to work.
Things went poorly, I was in the ICU for a week, then, after another week, they determined that while I was no longer going to die, I would not have a normal, unrestricted life. I was out of danger, they had done the obligatory minimum and would have been within their rights to tell me to scram and make room for somebody with gold-plated coverage. Instead, knowing that I had no means to pay for it, they agreed to attempt to restore me to my former level of health. So they performed another surgery, fixed it up the right way, and a week later I was home. Only downside: no SCUBA diving, ever.
The surgeon, anesthesia, and radiology all billed separately from the hospital and I paid them $30k out of my own pocket over the next 4 years. A nice lady in the hospital’s billing department told me I should have driven a harder bargain when I agreed to pay by the month beforehand; then she wrote off my entire $70k bill as indigent and told me to get back to class.
TLDR version: Received perfectly acceptable and not excessive care when I had insurance, then got way more than just the minimum life-saving care when I had no insurance. Go figure.