If you are referring to the overflow pipe when you say "16 inches", that could vary by manufacturer and tub model. According to some the standard height for tub valves is 28" above the floor with the spout being located below that. Install the shower switch valve at the same height as the tub valves as shown HERE. The shower head should be 72-78 inches above the floor. All of this can vary depending on the height of the user, or personal preference and aesthetics. Valves for a shower only are set at 48 inches above the floor.

Sorry. My question was related to the distance of the tub fill primarily (and the shower as well) from the wall which should match the distance of the drain from the wall, otherwise it would look odd.

If I need to see a tub spec sheet to determine this does it mean it is not the same for all tub manufacturers?

Why aren't you asking the manufacturer? You'd have that answer by now with no himming and hawing.

Go online and download the spec sheet.

Joe, not everyone has to make their tubs the same, so just do your due diligence and do as Ronald Reagan said: Trust but verify!

As I found out the position for different manufacturers is not the same. The reason I wanted to know this across manufacturers is whether I had flexibility down the road to drop-in replace one manufacturer's tub with another. But it seems like Delta is 14.5" from the wall whereas Kohler is 16" though both specify 32" as the depth. So the bathtub fill spout will not line up with the drain if you install it for one and replace it with another.