What are the differences between losarta hctz (hydrochlorothiazide) and losartan potassium?

A combo pill vs. ARB. Losartan HCTZ (hydrochlorothiazide) (= Hyzaar) is a combination pill that contains both losartan (angiotensin receptor blocker) and a diuretic (hydrocholorthiazide)--"water pill"-- whereas Loasartan potassium does not contain the diuretic.