Question from a non-English speaking newbie: what is the difference between the
Event Log and the Trace Log in the Diagnostic Logging
page (Central admin) 2010?
The event log is what you can view with the Event viewer. It can also contain events from other sources besides Project Server and SharePoint.
A trace log contains only information on your specific product, in this case Project Server and SharePoint.
When troubleshooting I always start with the event logs in the Event viewer and use a trace log for more detailed information