HETZBH,
Threadripper is basically EPYC, EPYC will support up to 1TB ECC, Threadripper supports ECC but likely will not support RDIMM (Registered memory which allows for the higher capacity DIMMs)
From the AMD Subreddit:
"Update: So we're getting contradictory information from different sources. An AMD product rep says that RDIMM/LRDIMM support is reserved for EPYC, but the Alienware rep says it takes up to 1 TB of RAM. I'm not sure how a 1 TB configuration is possible without some sort of registered or load-reduced memory, but at least we do know that ECC is supported. The AMD rep says that up to 256 GB is supported, which is still firmly workstation tier."
https://www.reddit.com/r/Amd/comments/6nd6iq/ryzen_threadripper_completely_upends_the/
Regardless you'd need 8 x 128GB RDIMM ECC (Keep in mind such modules would be extraordinarily expensive) memory modules to get 1024GB of RAM, I don't even know where you'd get such a module.
Seems a delineation between Epyc & Threadripper is memory capacity, but did you REALLY need (or intend to buy) 1TB of memory?