Infobarrel offers profit sharing whereas Ezine Articles doesn't. Both Infobarrel and Ezine Articles have Adsense placed above the fold but Infobarrel you get paid if someone clicks there. Ezine Articles allows you to blend your two links at the bottom of the article with the rest of the article whereas Infobarrel puts your links way off to the side making it unlikely for people to click-thru to your article. Ezine Articles gets more traffic but that's due to them already being a high well traffic site. When I first started my blog on height increase I submitted some articles to Ezine Articles to get traffic and backlinks but now I'm beginning to cross over to infobarrel.
Ezine Articles is a PR6 whereas Infobarrel is a PR5 both article sites suffer from the whole 10 backlinks per C-class IP but you can diminish that effect if you link to different pages(the power of content). Also, both sites increase the link popularity of your links as you continue to write new articles as all your articles are linked by your profile page. Ezine Articles makes it easy for people to republish your content. When people republish your content not only do you get your backlinks to your site but you also get a link to your Ezine Articles profile page.
The sig system is a strike against infobarrel as you really never want to link the same way to the same sites. So, you have to manually go in and create a new sig for each article. The only marketers who would use the same sig are affiliate marketers who link to the same page once with the anchor text and another with either click here or a stripped(no anchor text) link. However, infobarrels links are hidden off to the side so the click-thru rate should be very low.
Duplicate content diminishing link effectiveness aside, the main difference between Ezine and Info is the republishing. As for both you really want to write unrelated articles so they don't compete with your site so the click-thru rate should be pretty low anyways.
Affiliate Marketers: Ezine Articles
Authority Site Builders & Mini Site Builders: Infobarrel
Once you start seeing diminishing returns then you build another site but you will always get some benefit due to your profile page getting more link juice.