If there is a traffic jam it is because someone up ahead is driving slowly or poorly while you are an innocent bystander of the overcrowding situation.
If a colleague arrives late for a meeting it is because they are unprofessional. If you arrive late it is because you got a last minute phone call.
A waiter seems unfriendly which you attribute to a lack of professionalism or kindness. When you are unfriendly it's because you're having a bad day.
A teammate on a sports team underperforms on a play which you attribute to a lack of effort and commitment. When you underperform it's because the ball bounced the wrong way or someone on the other team shut you down.
Summary
A tendency to view the shortfalls of others as character flaws but your own shortfalls as the result of circumstances.
