What is the difference between "DS Directory Searches/Sec" vs. "LDAP Searches/Sec" in the NTDS Object?

Hello,

In the NTDS object, I see a DS Directory Searches/Sec counter and a LDAP Searches/Sec counter.  What is the difference?  Is the LDAP Searches/Sec issued by an LDAP Client/Application whereas the DS Directory Searches/Sec issued by some other client?  Can Performance Monitor tell me who issued these searches?

Thanks for your help! SdeDot