Light + proximity sensors.

 

Pretty sure All Moments have them.

 

All of them have the sensors, I think the newer versions have them with a lighter cover over them. They are mainly used to shut off the screen when it's near your face.

 

so a new hardware rev. any other difference besides this? ie performance etc.

 

I'm assuming it's a minor difference in the cover, either a small revision or differences among the individual pieces used. That or the OP just didn't see them on the other phone.

 

The three dots are on every Moment. Every one. All of them. Not a single Moment is without them.
However, depending on the light you are in, they are not as easy to see. They are quite obvious in natural light.

 

Every Samsung Moment made has them, if they are not there you are not holding a Moment. It is possible that the earlier models had a darker tint over them, as I bought mine the first day it was available, and maybe now they come with a lighter tint over them. I haven't gone to look at a newer Moment, so I don't know. However, the sensors were one of the very first things I noticed after removing the phone from the box, so the tint is not super dark.

They are all three light sensors (we think), one controls screen brightness according to incoming light, the other will shutoff the screen once it senses the phone is at your face, the other we don't know/ think it assists one of the other sensors.

 

I was going to ask about the dots but you have cleared it up for me...thanks y'all...