In fact, Minute Physics breaks down the differences between the observable and the physical universe in their trademark simplistic fashion (naturally, with lots of stick figures :). They explain that the physical universe may be infinite, but the observable universe is what is visible to us; like the line of the horizon which denotes the end of the area we can see, but does not preclude us from knowing that there is more world beyond what our eye can see.
My favourite section is where they explain that you and I are the centre of the universe:
"...the observable universe has a center - Us! We're at the center of the observable universe because the observable universe is just the region of space visible from earth, and kind of like how the view from a very tall tower is a circle centered on the tower, the piece of space we can see from here is naturally centered here. In fact, if you want to be more precise, EACH ONE OF US is the center of our OWN observable universe. But that doesn't mean we're at the center of The Whole Universe, just like the tower isn't the center of the world - it's the center of the piece of the world that it can see - up to the horizon."The whole video is just as awesome. Take a look.