Hidden is the older property from before we add RowLayouts. It's get/set. 

IsVisibleInLayout is a sort've resolved property that returns whether the column is actually visible the band is using RowlayoutStyle.ColumnLayout or RowlayoutStyle.GroupLayout Layout.

If Hidden is true, then IsVisibleInLayout should always return false. 

But if you are using ColumnLayout or GroupLayout, I think it's possible for Hidden to be false, but the column still not be visible in the layout for other reasons. For example, if the column is in a group and it's group is hidden. 

The HiddenResolved property is essentially the same as IsVisibleInLayout and works in any RowLayoutStyle. So if you want to determine if a column is hidden or not - regardless of the RowLayoutStyle, HiddenResolved is probably the best way to go. :)