While many use the terms “formula” and “function” interchangeably, they are not the same. A formula is an expression that is created to instruct Sheets. A formula starts with an equal sign, then contains the instruction. In =GT(A1,A2), the entire string is a formula.
A function is a premade formula that Google Sheets creates. It contains instructions behind the scenes that tell Sheets what to do. Often times, you can place a function within a formula. In this formula: =GT(A1,A2), the function is GT.