So do I want the button with the three horizontal lines, three horizontal dots, three vertical dots, nine dots arranged in a grid, the point-down triangle, or the point-right chevron? Generally these convey no information and I have to try each one to find the option I want. If it exists.
hamburger icon: originally, in older Android UI guidelines, provides access to a list of items that can be used to navigate between parts of a large UI. But at this point, pretty much evolved to mean "click to access a menu" on UIs that don't have a menu bar.
Three vertical dots: "More stuff that doesn't fit on a toolbar because the display on your current device isn't wide enough".
Three horizontal dots: click this item to access a dialog.
Point-down triangle: Select an value from a list.
There may be slight variations depending on the UI guidelines for the platform you are using (or designing for).
All enormously useful icons that provide specific context and meaning. I can't say that I've ever seen a piece of serious software that abuses those conventions.
