Just to be clear, in an AR platform. The 6.5 Grendel is in an AR-15, the 6.5 Creedmoor in in the LR-308/AR-10 platform.
Make sure the larger frame is not to heavy/ too big for what you want to do with it.
In a bolt rifle, the Grendel can be built in a micro action, but it will be some level of custom. A CZ527 in a 7.62x39 with barrel change for example. It really was designed around the AR-15.
The Creedmoor is a std short action. Several makers are producing it. Savage, Ruger, Cooper and Browning(intermittently).
The two rounds don't compare that well except for the 6.5 cal. The Grendel is, arguably, the most you can get from an AR-15 platform. That will create a fight, but you get the drift. The Creedmoor is just more round, but needs a bigger rifle. I have both, but the Grendel is an AR, my Creedmoor is a bolt rifle. I don't want to choose between the two.