Base vs S - weight

[Boxx]

Boring is usually something you do when you go to a bigger block.
And the 7.5mm bore increase seems like alot of aluminum to cut away.
I thought that was roughly how thick cylinder walls were in total.
Cutting half the cylinder wall away seems like bad mojo.
-- A 7.5mm bore increase seems like a different block.

On the other hand if an "S" has a bigger block, I would think
it would be more than 80 lbs heavier, especially considering
all the other heavier pieces like rotors and pistons adding weight.
80 lbs heavier total car doesn't seem like a heavier block.
Also, Paul said they were all the same exterior dimension.
-- Same dimensions and not much heavier seems like same block.

So which is it afficianodos?
- Is the "S" a different block, larger and heavier than the Base?
- Or does the "S" block have thinner cylinder walls than the Base.

It's got to be one of those two with a bore change.