Split button

A split button is a variation of a menu button. However, it does more than just its primary action.^[1] Split buttons offer a default single-click action while providing alternatives via a dropdown. They often use an arrow icon to indicate that secondary functions are available.

The only thing differentiating split buttons from regular menu buttons is some kind of visual separator between the button's primary function and the dropdown function. It prevents users from assuming the entire button will expose the dropdown.