What is the difference between hashimoto thyroid and thyroiditis? Are they autoimmune diseases?

Often same. 'thyroiditis' is an inflammatory process of the thyroid gland. Can be caused by virus, usually responds to anti-inflammatory medication and is self-limited. Hashimoto's thyroiditis similar, but is an autoimmune disorder where the antibodies attack the thyroid tissue, as though it was foreign. Over or underactive function could occur, but often becomes chronic and may need thyroid rx for life.
Different . Hashimotos is an autoimmune related hypothyroid state while a thyroiditis is an inflammation which can be caused by other etiologies including infection, meds, etc.