They are indeed the same, as the other answers state. Either one is an excellent choice for night photography and landscapes in general.
For example, the Israeli photographer Erez Marom travels the globe shooting night/landscape photos and the Samyang 14mm f/2.8 seems to be his "go to" lens for all things wide angle. He sells his work and some of the results are quite stunning.
In other words, it's a professional quality lens.
The lens exhibits mustache distortion; this can be mostly corrected in a program such as Lightroom using a custom lens profile. Depending on the scene, the distortion may not be obvious or it can ruin (prior to correction) the picture.
For star photos the Samyang/Rokinon will outperform the more expensive Canon 14mm f1.4 around the edges, as covered in this article.
The Canon 24mm f/1.4L II lens seemed like the perfect answer for my
star photography. All the reviews I read said that it performed well,
even wide open, with only moderate vignetting (which is important when
you want to stitch several images together into a panorama). By being
able to shoot at f/1.4, I could lower my ISO and greatly reduce the
noise I had been getting in my starry night skies.
None of the reviews mentioned the problem of coma. To my horror, I
noticed stars in my photographs that were shaped more like white doves
I can confirm this from first-hand experience with the Rokinon and the Canon.
As a side note, I've found the Rokinon to be a fun lens for HDR stacks due to its low-light performance (reduces the time the shutter is open on the +EV shots) and the wide angle.