To understand the leading of a heel turn, it is best to first understand what it is you want the follower to do. This may sound self-evident and oversimplified, but when a leader is unsuccessful, a lack of complete understanding is usually the culprit. So I suggest exploring that on a deeper level in studio, keeping the following things in mind as you do:
With the heel turn, a "missed" lead typically results in a side step for the lady, so you're on to something when you question the difference in lead between a heel turn-based reverse (or natural) and an open reverse. The answer is in the distinction between those two movements. In any turning figure there is a balance between the progression of the body through space and the timing of the rotation; Changing that balance affects the outcome.
With no turn, leading and following is a fairly straightforward endeavor: You move off of a foot, and your partner should be inclined to do the same, in the same direction and with equal distance. Turn complicates things because the more of it you have, the more you and your partner's steps will differ in size and direction, assuming you intend to stay in the same position relative to one another (e.g. closed position). This can be illustrated in the extreme by standing in a wide closed facing position, and having the man turn around while standing on one spot. The lady is forced to walk or chasse around a circle whose radius is exactly the length of the distance between partners.
A good rudimentary exercise in understanding the leading of heel turns, as well as spot runs, standing spins, and other rotational movements, is to do just that: First, have the man stand on a spot with the lady dancing on a circle around him. Then switch roles, with the man dancing around the lady (turning in the same direction). Then practice transitioning from one to the other without stopping, having the man decide when to switch each time, and leading each switch. Start with the widest possible radius (i.e. greatest distance possible in a closed facing position, or even in an open facing position with two-hand hold). Then if you're successful, start shortening the distance. The shorter the distance, the more subtle the distinction becomes, and the more the difficulty increases as a result. Practice first at the distance that is 100 percent successful, then go just slightly beyond. If you find yourself confused and frustrated, you've pushed too far. Back off and pace yourself, and it will eventually get easier.
A second exercise would be one where, instead of having one partner at the exact center of a circle, you have both partners chasse around two wider, concentric circles, i.e. curving chasses. Here, both partners must continually shift weight from one foot to another, but one partner's steps will always be slightly wider than the other's. The amount of difference depends on the width of the circles. Start with a very wide circle, so that the difference is almost unnoticeable, and then spiral inward, noticing the increasing difference in size of your steps. At its extreme, it becomes the exercise above, where one partner is at the center, taking no steps at all. Like the above exercise, practice switching roles, with the man leading the change from inside to outside of turn, always turning the same direction.
When you become skilled at both of these exercises, you will begin to see more clearly how you can lead and follow turns -- not only what direction to turn, but also who is turning around whom, and how big those circles are. Or put another way, whether you want the lady to close her feet and remain at the exact center of the circle while you turn around her, or whether you want her to move with you on a wider circle that's only slightly smaller than your own.
Put into the context of the open reverse vs. the heel turn reverse: The second step is the moment where the two of you will be drawing that circle, and that is the moment when
