Depends on how you compare things. 6.5 creedmore has a better selection of high bc bullets. High bc's mean more retained velocity, and less wind drift.
For example, if you look at the Hornady ELD-M. Best BC loads from Hornady
.308 168g, BC .523 2700fps, at 1000yds 100yd zero, 1305fps, -363.1in drop, 635 ftlb
.264, 147g, BC .697 2965fps, at 1000yds 100yd zero, 1771fps, -248.1in drop, 1024 ft lb
These were the 2 best factory loads I could find quickly.
You save 115in of drop and gain 389ftlb of energy with 6.5 vs 308.
If I was picking a deer rifle/long range target rifle I would go 6.5 creedmore. In my opinion its only limitations are for larger game. It was designed to get way out there for long range matches. It does have a big benefit there in my opinion.