I googled

"what's the difference between progressive christianity and buddhism"
(then later (here) PC and Unitarianism)

Buddhism:

http://www.reddit.com/r/Buddhism/comments/15wjgf/i_am_a_former_buddhist_turned_liberal_christian_i/

http://www.amazon.com/Going-Home-Jesus-Buddha-Brothers/dp/1573228303

http://www.comparativereligion.com/prodigal.html
(Prodigal Son in Chrisianity and Buddhism

http://en.wikipedia.org/wiki/Religious_pluralism

https://progressivechristianity.org/resources/redefining-christ-and-christianity-what-can-progressive-christianity-tell-us-about-modern-religion-secularisation-and-the-future-of-spirituality/

http://www.theharmonyinstitute.org/bookstore/comparative.shtml

http://www.everydaycitizen.com/2013/05/an_interview_with_progressive_christian_george_koukouris.html

http://www.everydaycitizen.com/2013/05/an_interview_with_progressive_christian_george_koukouris.html

http://www396.ssldomain.com/tcpc/review/review.cfm?review_id=235

http://www.patheos.com/Library/Mahayana-Buddhism.html

http://www.patheos.com/blogs/takeandread/2012/05/what-do-jesus-buddha-krishna-lao-tzu-have-in-common-a-qa-with-richard-hooper/