Difference between FMs CRM_MKTBP_ASSIGN_ATTRIBUT_TAB and CRM_MKTBP_CHANGE_BP

Hi Experts,

What is the difference between the functionality offered by the FMs CRM_MKTBP_ASSIGN_ATTRIBUT_TAB and CRM_MKTBP_CHANGE_BP?

I want to assign both attribute set and attributes to business partners through an ABAP program.

Thanks,

Diptee