Levels of plans in the Health Insurance Marketplace: Bronze, Silver, Gold, and Platinum. Categories (sometimes called “metal levels”) are based on how you and your insurance plan split costs. Categories have nothing to do with quality of care. (“Catastrophic” plans are available to some people.)
For each plan category, you’ll pay a different percentage of total yearly costs of your care, and your insurance company will pay the rest. Total costs include premiums, deductibles, and out-of-pocket costs like copayments and coinsurance.
Each category may include several types of plans and provider networks, like health maintenance organizations (HMOs) and preferred provider organizations (PPOs).

References

https://www.healthcare.gov/glossary/health-plan-categories/