How to read the select statement to understand the result

I am convinced that it is a very basic question, but I still have to ask it, making queries on the Oracle HR schema I notice that the result of these two queries is different: Expected result: I would like to know why this happens, when using the parentheses it gives me the result I want, while if I do not use the parentheses it gives me another record (Pat Fay) that does not make sense, how should I read this sentence to understand these outputs, thank you very much .