RtlEqualString - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTRTL_H

_Must_inspect_result_
NTSYSAPI
BOOLEAN
NTAPI
RtlEqualString(
    _In_ PSTRING String1,
    _In_ PSTRING String2,
    _In_ BOOLEAN CaseInSensitive
    );

#endif

View code on GitHub

This function is documented in Windows Driver Kit.