The difference is what the float switch has running through it. A float controlling RO water keeps on working. I have had one running 4 years w/o ever touching it. A float controlling saltwater is going to clog at times. You need to keep it clean from built up salt.
My Ultralife Float Switch is going on 100 years old and even having gone through a total white-out precipitation event it's still only frozen a couple times. (The reason to have a finite amount of water at your ATO's disposal.....5 gallons is my limit.)
I literally got it used when I started this system almost 10 years ago, so it's older than that....but I'm not sure how much older.....based on who sold it I know it could be as much as 25 years old and it's probably at least 15 years old.
In all that time and the white-out, I've never cleaned it once.
Reed-floats are tough as nails.
(I'm sure if I cleaned it once in a while, the thing would never, ever freeze.)