The difference between client-side and server-side latencies arises from how SQL statements are processed by PostgreSQL and YugabyteDB databases, with the extended query protocol allowing for more granular measurement of processing steps. The pg_stat_statements view primarily measures execution step latency, excluding parsing and planning steps, which can also take time. Understanding the application or client side timing requires knowledge of what exactly is timed, with the simple query protocol providing a straightforward measure but the extended query protocol including additional steps in the client-side observed latency. Server-side logging using the pg_min_duration_statement parameter provides a full picture of statement processing latency when the extended query protocol is used.