Great blog from Bryson Meunier addressing Adaptive vs Responsive design defining each in detail. See the link below, and I’ve paraphrased his summary below.
See on marketingland.com
“If you really want to pay attention to the mobile user experience and serve contextually relevant content to better serve your user and your business, dynamic serving through RESS or adaptive Web design (or mobile URLs) is better for SEO than responsive Web design. There are still workarounds for both, however, so if you can make responsive Web design work well for your users and your business (which isn’t easy, as I’ve said many times before), it’s better to do that than adaptive Web design or RESS.”