In physics, we usually distinguish between these two notions of universe as, one, the observable universe, which is everything whose existence we've thus far been able to confirm or observe, or could, in principle, observe if we pointed our telescopes at it, and two, the Universe with a capital U, or the whole universe, which is everything that exists, has existed, or will exist, anytime, anywhere, regardless of whether or not we are aware of it yet or ever will be.