Q. In SQL server, why is there a difference between the number of reads reported by STATISTICS IO and the number reported in a SQL Profiler trace?

A. The short answer is, the profiler trace shows *all* IO associated with a particular statement, including reads of system tables for schema information, permission checks, etc. STATISTICS IO only shows the reads of data pages that contain the actual data for each table named in the query. So, in general the two numbers will not match, and the Profiler number will usually be larger than the STATISTICS IO number.

This Q article has the details: Q314648: INF: Differences in STATISTICS IO, SQL Profiler and Sysprocesses IO Counters
http://support.microsoft.com/default.aspx/kb/314648