what do you mean size difference. the assemblies? i took a quick picture of them side by side. that is not the one. I also posted a link to where you can buy them as well. that is not what you need. you need a 2010-2013 outback foglight. part number: 84501AJ00A. go to subaruonlineparts.com or subarupartsforyou.com. much cheaper. but the latter is currently out of stock.