Hi @youxi
In case of HSE, the difference here is that "load key" is used for SHE keys (the term comes from SHE specification) and "import key" is used for other keys, let's say non-SHE keys.
The service ID is different:
HSE_SRV_ID_SHE_LOAD_KEY
HSE_SRV_ID_IMPORT_KEY
Regards,
Lukas