O/P
When the first P365 came out, it was called a P365 having a 3.1" barrel.
It has P365 on the slide and 10 round flat/pinky extension magazines, with an option to purchase 12 round extended magazines.
It is sometimes referred to as "Original P365", but still has P365 on the slide.
P365
The P365XL was next. It was called a P365XL having a 3.7" barrel.
It has P365 XL on the slide, has a removable top plate for an optic, and flat/straight trigger.
When you install an optic on this version, the rear sights are lost.
It's easy to tell them apart without looking at the stamp on the slide by looking at the length of the grip and slide.
The XL's slide overhangs the grip by ~.6" and accepts flush 12 round magazines.
P365 XL Gen1
The P365X was next. It was called a P365X having a 3.1" barrel like the P365 but adopted three of the P365XL's characteristics.
Those are the grip that accepted 12 round flush magazines, the same optic cut, and the flat/straight trigger.
It had only P365X written on the slide.
P365X Gen1
👉Here's where the
Confusion begins.👈
I'm not certain which came first but SIG Sauer began to make a Generation two ("Gen2") P365X and P365XL.
The P365X Gen2 is the same as the P365X Gen1, except that the optic cut was moved to in-front-of the rear dovetailed sight allowing it to remain when an optic is used.
P365X Gen2
The P365XL Gen2 is the same as the P365XL Gen1, except that the optic cut was moved to in-front-of the rear dovetailed sight allowing it to remain when an optic is used.
And the "L" was dropped from being on the slide, leaving only "X".
This was done by SIG Sauer to... A) Cut costs, B) Differentiate from the original P365, C) Both A&B.
P365XL Gen2
Hope this helps!
Certain I'm missing the SAS and other information. Others can feel free to copy and make changes and add to if necessary.