its the same text, same words, same images. it hasn't changed at all. but one layout gets punished and the other doesn't? its nuts. google are punishing the design, not the content. how can they not lose a few good sites along the way?
IMO, that's one of the reasons they made this announcement so public and so specific. This isn't about secret sauce... and it's not about punishment. This is about user experience that Google wants to improve. Google needs to be concerned about the satisfaction of its own users, and I think they've discovered that searchers don't like interacting with sites that are ad-heavy up at the top.
So Google is making this algo-change public enough that those sites with good content, which they'd rather not lose, might have a good idea what to fix. It's likely also that Google will be taking a closer look at the kinds of sites that this set of algo changes affects, to further calibrate its own algorithm in this area. Google will probably be further comparing sites with large blocks of ads, vs sites with large images, vs sites with lines of small ads intertwined with internal navigation, etc etc.
Panda is a statistical algorithm, and Google is using it to look at user behavior, at what kinds of decisions users make and where and when they make them. Google will further refine the algo, factor by factor over time. Examining above-the-fold behavior in isolation will help Google get more granular with regard to it changes in the above-the-fold area.
Changing the ads on your site won't automatically fix your rankings, though, if, say, you don't have good content or if your backlinks are weak... but it may keep you from getting filtered out if you know that other things are OK. If you've got some big images that you feel help the user experience, I'd say keep them. If these big images are helping the user, Google should ultimately sort that out.
On the other hand, I've seen sites overloaded with so many big images that haven't been optimized for the web that pages took 15-seconds to load on DSL. Loading speed is another factor, but these things do interrelate. Here's where you have to have both some knowledge and the courage of your convictions. If you build your site with an eye towards relevant, good quality content and good user experience, you will develop some self-awareness about a site's strengths and weaknesses that should guide you. But this is by no means easy.
Google has made other changes, not specifically announced, in this same period, which might also adversely affect your rankings. I'm thinking that I'm currently seeing changes probably related to backlink quality and/or user engagement on the site... but that's only a guess, and these factors might apply differently on different kinds of sites.