Hey,
My third eye has been active on a daily basis for quite a while now, whereas crown experiences are less common. The line between the two is a little gray. Somewhere around the hairline is a good estimate for where one starts and the other ends - as far as surface level sensations. Deeper inside, the third eye and crown are two branches of the spinal nerve. The third eye region goes forward from the middle of the head and includes the front part of the head including the maxillary (top) part of the jaw. Third eye sensations can be felt anywhere in the whole region, including in front of the face, inside the forehead, the nose, etc.
The crown branch goes straight up through the top, and above the top of the head. Crown sensations can be all around the top of the head, but are strongly centralized in the middle of the head. As if a pole were running straight up and down through you. The part of that pole that is in the upper half of the head is the crown region. Just like you might feel the third eye sensations all over the front of the head, the crown sensations might be felt all around the top of the head.
I notice you have written this post in the "self pacing" forum. Yogani has given us caution about going with our intention to the crown too soon. But it's fine to start getting sensations in the crown region. In fact it's a wonderful and even deliberate byproduct of doing the AYP practices. The crown path that goes up to the top of the head is opened by proxy of our daily attention on the root-to-brow path. We don't pry the crown open, but we also don't resist or worry about its natural opening. I suppose everybody's different, but for me it has opened up a couple of times - and it's wonderful, and also high energy. Afterward I take it easy for the next few days and no problemo. Just like that, the guru is in us, we go at our own comfortable pace.