The initial resemblance really just comes down to 2 fairly pragmatic design decisions. We’ll use 2 side solid propellant boosters and we won’t redesign them from scratch because they work. And, we’ll use the same foam insulation on the rocket that we used on the STS liquid propellant tank because it also works…furthermore, we won’t try to paint over the orange insulation because we know that that doesn’t work very well.
