they also share the same parent cartridge ...as does the 270 and the 25-06
The 280 was designed with a greater length to the shoulder to prevent some idiot from chambering a 280 in a 270 chamber.
Guys.....all this info is available online..
Get yourself and computer and an internet connection,....oh wait......
http://www.saami.org/PubResources/CC_Drawings/C and C Dwgs - TOC - Rifle.pdf