mssql_fetch_array() vs. mssql_fetch_assoc

In terms of performance which is faster. mssql_fetch_array($var,mssql_assoc) or mssql_fetch_assoc()? I read in the manual that mssql_fetch_array() isn't noticably slower than mssql_fetch_row(), but I didn't see anything about mssql_fetch_assoc() in terms of performance. I was wondering if anybody already knew what the performance differences were.