PHP变量钩子

i was wondering what the difference is when u put a variable in another variable with the notation. So i have a variable "Body" and in there is HTML tags, text and PHP variables, ive found out i can put them in between hooks but that they would react exactly the same. Example:

In this piece of code the variable is in between { } hooks.

$body = "
             <table style='border: 1px;'>
             <tr>
             <td><b>Naam:</b></td><td>{$naam}</td><br>
             </tr>
             </table>"

And here it is not.

$body = "
             <table style='border: 1px;'>
             <tr>
             <td><b>Naam:</b></td><td>$naam</td><br>
             </tr>
             </table>"

And this both reacts exactly the same. So can anyone tell me if this has an actual use, or that this is just like all PHP with the 10 ways to do the same thing.

Thanks in advance.

Addition

This is not a duplicate ofThis. It does not explain the part of why a variable inside of a variable can be put in between curly brackets.

Usage of curly braces inside " is particularly useful when you want to add complex instruction or access object/array properties.

This code will perfectly work

<?php echo "Test {$foo['bar']}"; ?>
<?php echo "Test {$foo->bar}"; ?>

While this one will fail

<?php echo "Test $foo['bar']"; ?>
<?php echo "Test $foo->bar"; ?>

So yes, it's not particularly useful if you are accessing a simple variable, but when you want to play with array and object, it's useful.