I might be wrong but from what I am guessing from MassWildLife is that they set up the C.P.R. for adults since kids are taking over the weight pins for last few years. So, they wanted to find out more data about fish. So, hence, the reason why they had to set up the C.P.R. So they can draw more adults to reference/boost MassWildLife's data on fish.
Anyway, C.P.R. is different category from weight pins. I am not sure about C.P.R. is similar with weight pins. However, all I know is that if you cared about pins (for gold pins or Angler of the year award) and you will want to be weight them. If you don't care and wanted to released them and you are guarantee to get C.P.R. pin.
Hope it is clear up some things that you are confused about it.
Awesome
http://www.onthewater.com/massachusetts-adds-release-category-awards-program/
What do ya know, look what I found
http://www.onthewater.com/forecasts/2012/05/massachusetts-new-hampshire-and-maine-fishing-report-5-17-2012/