Watchlords

Miyota 9039 VS 9015

As you can see in the chart above, the Miyota caliber 9039 and 9015 are nearly identical with exception to two main differences:

The calendar complication
The height of the hand stack

Date:

The most notable difference when the 9039 and 9015 are compared is that the 9039 does not have a date option. The 9015 is available with 3 date options. This is not to say that a watch with the 9015 has to have a date. Before the 9039 was introduced, watch brands seeking to design a no-date timepiece would simply cover the date wheel with the dial. This Borealis Olipsio is a good example of using a 9015 without a date aperture cutout in the dial – now they can just use the 9039.
Crown Clicks:

Because of the lack of a date setting position, the crown on the 9039 only pulls out one click for time setting. The 9015 has two time setting positions: position 1 for adjusting the date and position 2 for the time.

This is why using a 9015 without a date is not ideal because it will still have the calendar setting position and functionality.

https://calibercorner.com/miyota-caliber-9039-vs-9015/

A no-date 9015. I am a fan.

I get why the 9039 may be appealing over a no-date 9015 if you don't want to mess with a 2 position crown. The 0.35mm difference in hand stack height is so minute no one will ever notice. But it's always great to see more options!