The key difference between euthanasia and assisted suicide is that in cases of assisted suicide, the individual receives assistance (or materials), but ultimately voluntarily and directly causes their own death. In euthanasia the individual does not directly end their life, but another person acts to cause the individual's death. This can either be done with consent or without consent. For example, in a case of euthanasia, a physician could inject a person with a lethal dose of morphine. In a parallel case of assisted suicide, the physician would supply the medication to the patient, and the patient would administer the dose to themselves.
Euthanasia is currently illegal in all 50 states of the United States. Assisted suicide is legal in 10 jurisdictions in the US: Washington, D.C. and the states of California, Colorado, Oregon, Vermont, New Mexico, Maine, New Jersey, Hawaii, and Washington. Its status is disputed in Montana, though currently authorized per the Montana Supreme Court's ruling in Baxter v. Montana that "nothing in Montana Supreme Court precedent or Montana statutes [indicates] that physician aid in dying is against public policy."