“I can do this work” – confidence.

“Only I can do this work” – overconfidence.

Confidence is more about respecting the potential of yourself while overconfidence is about disrespecting the potential of others.

Being confident helps you reach your goals while overconfidence takes you further away from your goals.

Confidence – I can suitable for this job.
Overconfidence – only I can do this job.

Confidence – believing in your selves and hard working to reach your achievement.
Overconfidence – not knowing anything about it, ignoring facts and just going on to reach your achievement.