Scalar: It is denoted by $ symbol. Variable can be a number or a string.
Array: Denoted by @ symbol prefix. Arrays are indexed by numbers.
The namespace for these types of variables is different. For Example: @add, $add. The scalar variables are in one table of names or namespace and it can hold single specific information at a time and array variables are in another table of names or namespace. Scalar variables can be either a number or a string
