I would add that in a heel lead, normally you (and your partner) arrive onto a bending knee to make the path of rise gradual, and only end up with your body over a fairly straight leg during the 2nd or 3rd step (depending on type of figure).

However, if the lady is dancing a heel turn, then both partner's legs remain relatively straight during the arrival on the first step - the man doing this is a key component of the lead for a heel turn. But it's important to note that only lady's heel turns have this property. When the man is himself dancing a heel turn both partners arrive into a bending knee as the rise in men's heel turns occurs out of the turn rather than into it.