I was trying to find out the same thing. I contacted CINEDIGM (manufacturer), and just got a response today from marketing assistant Lindsey Coven saying,
"Hello Jonathan, Thank you for your interest in Farscape. The box set includes the same masters from the 2011 release."
I also cross-referenced all the material from the 2011 blu-ray release and the 15th Anniversary edition, and everything is the same. No new content, other than new packaging.