(1) ACE leverages hardware virtualization support, including an MMU, to enable confidential virtual machines. In contrast, Keystone is designed for simpler processors that rely on just machine/supervisor/user privilege levels and physical memory protection (PMP), making it more suitable for process-based enclaves—similar to architectures like Komodo or Intel SGX. In that sense, ACE is conceptually closer to Intel TDX, but tailored for a different domain: embedded systems rather than cloud infrastructure.

(2) In ACE, the architecture and code are simplified to facilitate formal verification.