Based on user and expert reviews from Best Backup Reviews and Eileen's Lounge : Performance
The Utility and Implementation of Macrium Reflect Portable (64-Bit)
System Migrations: If you are moving a user from an old laptop to a new one, you can boot the portable tool, clone the drive, and be finished in minutes.Emergency Recovery: When a client’s computer crashes, having a 64-bit portable tool allows you to attempt data retrieval or partition repair without needing a working OS.Technical Audits: IT auditors can use the portable version to take "snapshots" of systems for forensic or compliance purposes without altering the host environment. How to Create Your Macrium Reflect Portable Drive
It leaves no registry entries, temporary installation files, or background services on the target computer.
Explain the between the bootable rescue media and the portable app.