No else after if - Bad practice?

Is it bad practice to not follow an if-statement with an else-statement? Is it purely preference, or are there standards (such as for readability, or sustainability, etc..) that encourage complete if-else statements?

Recently i found myself using more if-statements without an else, but its for code that will break/return, such as

if(x == y) return z;
//otherwise do the rest of the code below

as opposed to

if(x==y){
 return z;
}
else{
  //execute code
}

Does it make any difference for the compiler if i do if-else or just an if?