The Di series is their distance iron....
Ci is more for control shaping etc.....
As stated the lofts are stronger ie Pw 47 Di 48.5 Ci (Reliable info but don't bet the farm on the numbers)
I bought Di5's several years ago and they are just long as hell irons....Noticably longer when I huff and Puff before the shot...lol
Di5 will certainly shape shots as well...The Nano graphite UST shaft in these irons is terrific...
I am ready to move up into newer Staff irons this year, but I do not want to lose too much distance with my normal swings....
From experience who would recommend Ci or Di - and why - shaft info include in answer please...
Thanks
Bill