If I have a statement block like this:
if (/*condition here*/){ }
else{ }
or like this:
if (/*condition here*/)
else if (/
You already gave the answer yourself. if/else is for true/false result, like is an int=2 or any other possible int value, and if/elseif is for more than 2 results, like an int=2, and int=3 and so on.
Also it groups the context of a variable. You could check every single result like
if (a == 2) { do one thing };
if (a == 3) { do another thing };
...
if (a != 2 && a != 3 ...) { do something else };
With if/else/elseif it's better readable.