based on the pictures listed on sellers sites, samsung's site, and the ones i recently received from CDW. I got the E models from CDW and they're white boxed. CDW doesn't even list the B versions. Also got E versions of the 970 evo. I'm thinking the E versions are more OEM parts vs standard retail. newegg and amazon only seemed to have the E versions on third party sellers.
I can't say for sure, this is just my guess based on observation. Oh, i only ordered the 250 GB 860 evos so i can't compare price much.