Which one is less intrusive?
Which one uses less resources?
What is their process of action how they protect?
1 - SD
2 - SD
SD is whole-disk virtualization software.
ReHIPS is HIPS + Isolated Environment (IE) execution.
Isolated Environment = execution environment with improved Limited User Account access; IE has even more tight file system and registry access than LUA.
User can sign into Protected Admin account, but still run applications as Limited User inside Isolated Environment; there is no need to sign-out from PA account to execute a program as a limited user.
The perceived inconvenience with ReHIPS Isolated Environment is for best protection you should run each program independent of every other program = in its own Isolated Environment. Once you get used to it, then it doesn't seem as much a nuisance; it is psychological I think...
ReHIPS, by extension, is probably US DoD compliant since it uses one of the most important built-in Windows security mechanisms.
The only other security soft that can make a similar statement is AppGuard. It isn't DoD compliant. It just got awards from Homeland Security. So, really, not even close.
AppGuard + ReHIPS = only way I can see physical system being persistently infected is by user mistake; no exploit, no reflective memory injection\fileless malware, no malicious word documents\emails\PDFs, no ransomware, no - no - no !
Same with SD in terms of physical system protection, but booting into Shadow Mode all the time - some find inconvenient.
Shadow Defender, ReHIPS, AppGuard - they are all in the same 1st-rate class of available protections.