As far as I know, you can't really tell just by a few pictures.
I THINK the following is true, but if someone knows different, please feel free to correct me:
241 casting heads = LS1
243 casting heads = LS6

The LS6 intake swaps over easy-enough. Most LS1 guys switch to the LS6 intake (no EGR hole in the top of it) and it came on 02+ LS1's OEM anywya.

I think the only difference between the LS1 - LS6 are a few internal passageways in the crank to allow for better breathing of the oil, a hotter cam, and better heads. It is all internal as far as I know.