See the map below - Miami Beach is a separate island that is really only accessible by car (as is the rest of Miami) - it's long, and most of the hotels are located on the beach - there are good restaurants on the island (highly recommend Mister O1 for pizza, though there is also a location in Brickell) - Miami Beach is divided into South Beach, "Mid-Beach" and then further northern areas, like Bal Harbour (further north than the screenshot below). Downtown Miami, also known as Brickell, is on the mainland and is seen on the left-side landmass. Brickell is really the south side of the river, but it doesn't really matter as most things are clustered on the shores of that river that you can see. There are no beaches here - just a lot of hotels, offices, residences, and shopping malls - this is where the skyscrapers are, etc. If you stayed in Brickell or Downtown, you would need to drive to a beach.