Solved What is the difference between these functions?

1°: $player->setDisplayName(...);
2°: $player>setNameTag(...);
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It may sound silly, but in my view (or reading ) there is no difference

 

The NameTag is just the Tag above your head.
The DisplayName is like a NickName, it's shown in the PlayerList and the escape screen.

 

Display name and username are separate properties because the username can be used for identification and therefore its mutability is not desirable.

 

Thanks for the help!