Except in this context its a valid comparison. Apples and oranges are both foods. They may taste completely different, but they both provide nutritional value. Same with this conversation/article. Both are application suites. They may look different and have different requirement (net access...yeah yeah Google Gears, etc) but they both allow you to create/edit documents.

On a side note, I think in many cases the apples to oranges comparison isn't sufficient. How about hamsters and hand grenades?