When to use split button vs more options button?

Question

When do you typically use split buttons vs a button with more options (ellipsis)?

From how I understand it, split buttons are for grouping related options with one most common option surfaced?

Answer 1

Summary

The use of a bipartite command button with an ellipsis button is non-standard, so there is no official right answer, except, maybe, don’t use a bipartite command button with an ellipsis because it’s non-standard. Frankly, very rarely could I see it being helpful, so just use the arrow.

The Standards

According to the Windows 7 User Experience Interaction Guidelines, with a split button, “users click the triangle to display variations of a command in a drop-down menu” (p872)

That’s pretty straight-forward.

Given there is no standard for an ellipsis button, what could it mean to the user?

Generalizing from the Standards

The same Win 7 standards say that “ellipses mean incompleteness.” For buttons, an ellipsis means “a command needs additional information [before it can take effect]” (p10). Apple OSX Human Interface (2012) likewise say an ellipsis “indicates to the user that additional information is required before the associated operation can be performed.” Usually the user provides this additional information in a dialog box.

So, this implies that an ellipsis button provides the user with the ability to provide more information about how a command is performed, probably through a dialog, since that’s what ellipses usually mean and it distinguishes the behavior of the ellipses button from the arrow button.

So it’s something like this?

However, the Win 7 standards themselves point out (and this example demonstrates) that using the split button instead is often “a simpler, more direct way to present the options” than using a dialog. So why would you ever want to have an ellipsis button?

Well, maybe if the additional information is too complicated and varied to reduce to a list of menu items. Maybe something like this:

But even here, you'll usually be better off having split button with menu items for the common simple variations, and also a menu item to access the dialog for the (rare) complicated variations:

The need for the dialog should be so rare that it’s okay to require two clicks to get it.

Bottom line: I can imagine a use for an ellipsis button on a bipartite command button, but it should be so rarely needed, I would avoid it as non-standard, or, at least, only use it if usability testing showed users understood it well.

Who is Using Ellipsis Buttons?

Frankly, I haven’t seen ellipsis button used on a bipartite button, so it’s not only non-standard, it’s probably non-conventional. If some designers are using ellipsis buttons, perhaps they’re confusing bipartite buttons with command bars. In the Windows 10 User Experience Guidelines for UWP Apps, an ellipsis button on a command bar means “more” (p87). That is, it reveals additional less frequently used commands.

So maybe some designers are treating a single command button as a command bar with one visible menu item? If so, that makes the ellipsis button synonymous with an arrow button: it shows more commands on a drop down. That’s an irregularity we don’t need. I’d avoid it.