There is a difference in the way that PHP handles single and double quote marks when using the echo statement.
For example :
$var = ‘test’;
The statements echo(‘$var’); and echo(“$var”); will generate different results.
echo “\$var is equal to $var”;
will display $var is equal to test
echo ‘\$var is equal to $var’;
\$var is equal to $var.
In the case of the sinlle quotes, the variable name is displayed as is.