SELECT SINGLE VS SELECT UP TO 1 ROWS

By seeing the Heading (select single vs select up to 1 rows) many of you might suggest me to search the forum. I did search the forum and found few threads regarding the differences but I'm confused with the fact that in few threads it says SELECT UP TO 1 ROWS is faster which is marked as right answer(select single vs select upto one row | SCN) and in few threads it says performance wise there is no difference ( "SELECT SINGLE" vs. "SELECT UP TO 1 ROWS" | SCN ).

Which is right?