Comparing Two Algebraic Expressions

Maria is thinking of a number, which she denotes as $$x$$. She triples the number and then adds 5 to the result. This can be expressed as:

$$3x + 5$$

Sam, on the other hand, takes the same number, squares it, and subtracts 4. This can be expressed as:

$$x^2 - 4$$

What is the relationship between Maria's expression and Sam's expression?