What is the difference between Abdicate and Resign and Relinquish?

What is the difference between Abdicate and Resign and Relinquish? :
Abdicate : 

( 1 ) Resign from or formally renounce the throne

The King of Egypt abdicated about thirty years ago. 

( 2 ) Formally give up power or a high official position

He has abdicated all responsibilities in the affair. 
Resign : 

( 1 ) Give up a job or a position

I resigned my post as Chairman of This Company. 

She resigned her directorship and left the firm. 
Relinquish : 

( 1 ) Give up or cease to feel or practice something

You should relinquish bad habits. 

The relinquished their struggle for power. 

( 2 ) Give up or renounce a claim or surrender something 

I relinquished the possession of the house in favour of my brother. 

( 3 ) Release or cease to hold somebody or something

Do not relinquish your hold on her.