Could anyone clarify the difference between reference architecture, building block, and EA pattern?

Hi

http://www.linkedin.com/groups/Could-anyone-clarify-difference-between-36781.S.205628561?view=&srchtype=discussedNews&gid=36781&item=205628561&type=member&trk=eml-anet_dig-b-pop_ttl-hdp&ut=39wCdE33U4CRA1&_mSplash=1

;;_))