OTG is over-processed to the point of being comical. Compare her vocal sound on the first lines of the song to how she sounds in the first "look at me I'm never comin down". Totally different, because there's so much processing on the rest of the track she might as well be singing through a vocoder.
Like Water has more natural vocals (don't get me wrong, there's still some processing there, but it's a WHOLE lot less).
If you have two tracks to showcase a singer who's supposed to be one of your main vocals, why not just let them sing, why distort the heck out of their voice? idgi. So Like Water for me. At least when she's in full belt, you can actually hear what she sounds like.