Difference between Credit Limit of FD32 and OB52

Hello All,

I am configuring Sales Credit management but i got confused in these two T-CODES while assigning credit limits. What is the difference between FD32 Credit Limit and OB52 Credit Limit. If we assign credit limit in OB52 then why we assign in FD32.

Also kindly help me how to assign roles for credit limit means authorization in sales credit management.

Best Regards

Roshan