Replying to a post is extremely confusing and often results in the user not choosing the right option

There are two ways to reply to a post in the forum software. These are illustrated below, and they do different things. The designers of the forum software knew that they do different things, but never informed the used by indicating what the difference is in the user interface. They never told the user that the two different methods do different things. And so, often users select the wrong reply method, and this causes a lot of replies to wind up “un-threaded” and at the top of the post, just under the original post. This makes following the discussions in some chronological order nearly impossible. It has taken me 8 months or more since the new forum was created to figure this out, and I’m sure most users have not figured this out, making many threads nearly impossible to read in a meaningful order.

Example 1: from the thread 

Selecting the reply shown in the screen capture puts the post at the top of the thread right underneath the original question. But it doesn’t say that’s what it does.

Example 2: same thread, but now there are two different Reply buttons, and no indication of which one does what. The forum designers did not do the users a favor. The button that says “Reply” with the curly arrow creates a threaded reply, with the reply being shown underneath this particular comment, while the one that says “Leave a reply...” puts the reply at the top of the thread, underneath the original post.

Please re-design this so that it is clear what each reply method does.