It's going to be two pages ultimately. If you're comparing features, you don't care about the how.
Right now we're keeping all the data in a JSON file that we massage into a chart. Massaging it into a true feature comparison chart, along with a rosetta stone, should be a simple matter of programming. Same thing with the GNU/POSIX/BSD rosetta stone we're working on.
We're also working on a GNU grep vs. POSIX grep vs. BSD grep phrasebook.