The short version
Same climate hardware, same tracking, same subscription. The only meaningful differences are form factor (integrated system vs cover-on-existing-mattress) and price (~$3,500-5,000 vs ~$2,200).
When Pod 4 is the right pick
If you are replacing your mattress in 2026 anyway, the integrated Pod 4 system delivers the cleanest fit and a coordinated multi-year build. Pay the premium for the unified product.
When Pod Cover Pro is the right pick
If you have a mattress you like and you want Eight Sleep climate and tracking on it — Cover Pro is the rational choice. Same software, same climate range, ~40% cheaper, and transferrable to your next mattress.