Yes. Under U.S. Department of Agriculture standards, “hamburger” means chopped fresh or frozen beef, with or without added beef fat and/or seasoning. It may not contain more than 30 percent fat and may not include added water, phosphates, binders, or extenders.
Everyday restaurant “hamburgers” are usually beef patties on a bun, but plant-based or other-meat sandwiches are labeled differently and are not USDA “hamburger.” The main legal difference from “ground beef” is that hamburger may have beef fat added separately.
Source: 9 CFR § 319.15 — Miscellaneous beef products (Legal Information Institute)