title: What is the difference between server key and legacy server key in FCM(Firebase cloud message )
body: <p>I little confused with the server key I have to use in the in the FCM. There are showing two server key now.Please check the screen shot of the page<a href="https://i.stack.imgur.com/QY4QW.png" rel="noreferrer"><img src="https://i.stack.imgur.com/QY4QW.png" alt="enter image description here"></a></p>
  
  <p>In the picture above shows the server key and legacy server key which one I have to use.Anyone has any idea what is the difference between the two?</p>
  
  <p>Thanks</p>