Rugby laws can be confusing at times and the latest law book runs to 146 pages. It doesn't help that some of the terminology commonly used isn't completely consistent with the law.
For example, Law 14 defines a tackle as follows -
REQUIREMENTS FOR A TACKLE
- For a tackle to occur, the ball-carrier is held and brought to ground by one or more opponents.
- Being brought to ground means that the ball-carrier is lying, sitting or has at least one knee on the ground or on another player who is on the ground.
- Being held means that a tackler must continue holding the ball-carrier until the ball-carrier is on the ground.
With this definition it should be clear that the "choke tackle" described in your first sentence, isn't in fact a tackle at all.
However, at this point if it's just the ball carrier and one (or more) opposition players/would-be tackers involved then it's not a maul either and it remains "open play."
Law 16 defines a maul as follows -
FORMING A MAUL
- A maul can take place only in the field of play.
- It consists of a ball-carrier and at least one player from each team, bound together and on their feet.
- Once formed, a maul must move towards a goal line
The key requirement here is that a team-mate of the ball-carrier needs to join in the "chock tackle" for a maul to be considered formed. At this point the referee would usually shout "Maul".
For the referee to then award a scrum to the opposition team, the maul must end unsuccessfully.
Law 16 lists the conditions for this to occur -
A maul ends unsuccessfully when:
a. The ball becomes unplayable.
b. The maul collapses (not as a result of foul play).
c. The maul does not move towards a goal line for longer than five seconds and the ball does not emerge.
d. The ball-carrier goes to ground and the ball is not immediately available.
e. The ball is available to be played, the referee has called “use it” and it has not been played within five seconds of the call.
With a well worked "choke tackle", the opposition will often have the upper hand and the maul will end unsuccessfully for the ball-carrier's team. Hence the opposition being awarded a scrum.
A few further comments -
Assuming that your comment about "more conventional mauls" refers to what happens after (proper) tackles, then these are actually called Rucks and are covered in Law 15.
You might observe that I haven't used the terms "attacking team" or "defending team" in my answer. That's because the law definition of these isn't what you think it is. It's not about who has the ball - it's about in which half of the pitch play is currently taking place!