Design implications of Balloon Tooltip vs Rectangular Tooltip

I'm using a tooltip for a validation message and trying to weigh different design options.

I'm curious because in this walkthrough on using MaskedTextBox.ValidatingType, they go out of their way to suggest using ToolTip.IsBalloon = True, even though the distinction would otherwise be immaterial to the example.

Do Rectangular vs Balloon Tooltips afford different kinds of usages?

My guess would be that rectangular tooltips are more often used for supplemental information whereas balloons with an arrow indicate information directly related to a field or value.

Anybody have any input on the differences/usages?