What is the difference between checking if a variable is not NULL versus checking if it is an empty string in PHP?

When checking if a variable is not NULL, you are verifying if the variable has been assigned a value or not. On the other hand, checking if a variable is an empty string means you are specifically checking if the variable holds an empty string "" as its value. It's important to differentiate between the two checks to handle different scenarios accurately.

// Check if a variable is not NULL
if ($variable !== NULL) {
    // Variable is not NULL
    // Do something
}

// Check if a variable is an empty string
if ($variable !== "") {
    // Variable is not an empty string
    // Do something
}