Purge is the stronger sanitization class — techniques intended to resist laboratory-level recovery attempts appropriate to the media type. In practice that often means cryptographic erase on self-encrypting drives, or overwrite / sanitize commands suited to HDD, SSD, and NVMe, chosen for the technology rather than a one-size script.
When it fits
The common enterprise and colo bar before reuse or resale of drives: media may still function as storage, but residual data risk is reduced to a level policy accepts for leaving controlled custody or entering secondary markets.
Reuse / resale note
When finance wants residual value on flash or disks that remain sellable devices, Purge (where media and policy allow) keeps buyback in play. Destroyed drives are debris, not inventory. Coordinate media policy with server buyback so the residual model does not assume every bay is zeroed.