Freestanding units do just that — they stand freely, often with casters for greater mobility. On the other hand, built-in appliances are designed to be integrated into a kitchen counter, outdoor kitchen, or bar island; they’re a little smaller, but operate pretty much exactly the same. Built-in units must always be front-vented for proper exhausting of heat, and you will need to account for any electric and drainage needs specified by the model. Their freestanding cousins aren’t so picky about venting requirements — even so, err on the side of caution with enough room for proper exhaustion.