Are you familiar with "Hidden" sections? Essentially you create a sub header (in usually the last area of a page), and set the dependency to hidden, as described by Ernst. Fields occurring after this Hidden section will then be invisible.
So what I do then is create a Check Box (bEditMode is my name). I place that check box after that Hidden subheader, so it is not visible.
I then have two triggers. An "OpenEdit" (Updating an entry) trigger that simply sets that check box, and a "OpenView" (opening An Entry View Card) trigger that simply resets it. The bEditMode checkbox default value is set true, so that this method also will work for when creating an entry.
Then set the dependency of the field or fields you want visible or invisible to the bEditMode check box. And the field(s) you set will only be visible in the mode you want it do be.
And by the way, the bEditMode is also a great field to use as the dependency for that Hidden section field, setting the section invisible with either/both values of bEditMode.