Aluminum has gain wight and ...interestingly...

[Julien]

The Aluminum may be thinner but has porked up a little. Also oddly the GPS and Cell now have the same weight indicating that the GPS may be a neutered Cell version (same hardware).

• Series 3 Aluminum 38mm GPS 26.7g, Cell 28.7: 42mm GPS 32.3g, Cell 34.9g
• Series 4 Aluminum 40mm GPS 30.1g, Cell 30.1: 44mm GPS 36.7, Cell 36.7g

 

[oeagleo]

The Aluminum may be thinner but has porked up a little. Also oddly the GPS and Cell now have the same weight indicating that the GPS may be a neutered Cell version (same hardware).

• Series 3 Aluminum 38mm GPS 26.7g, Cell 28.7: 42mm GPS 32.3g, Cell 34.9g
• Series 4 Aluminum 40mm GPS 30.1g, Cell 30.1: 44mm GPS 36.7, Cell 36.7g

Possibly from the addition of the sapphire glass on the reverse rather than the composite, and maybe the titanium "ring" for the ECG? Not sure if the additional height of the watch body would contribute too.

 

[Vanilla35]

The Aluminum may be thinner but has porked up a little. Also oddly the GPS and Cell now have the same weight indicating that the GPS may be a neutered Cell version (same hardware).

• Series 3 Aluminum 38mm GPS 26.7g, Cell 28.7: 42mm GPS 32.3g, Cell 34.9g
• Series 4 Aluminum 40mm GPS 30.1g, Cell 30.1: 44mm GPS 36.7, Cell 36.7g

Likely increased battery capacity adding most of the weight. I doubt chip differences would contribute very much.

 

[Julien]

Likely increased battery capacity adding most of the weight. I doubt chip differences would contribute very much.

The S3 models had the same battery but a different weight in the GPS and cell versions. So the cell chip/antenna must have added to the wight in the S3s. So why do the S4 GPS and cell weigh the same? Me thinks the S4 GPS probably has the cell hardware (probably cheaper to manufacture one chip set) but neutered hardware.

 

[Vanilla35]

The S3 models had the same battery but a different weight in the GPS and cell versions. So the cell chip/antenna must have added to the wight in the S3s. So why do the S4 GPS and cell weigh the same? Me thinks the S4 GPS probably has the cell hardware (probably cheaper to manufacture one chip set) but neutered hardware.

Oh I thought there were small differences in battery between GPS and cell models. I may be thinking series 2 to series 3 transition though. Other changes would be display, etc.

It was indeed rumored that all series 4 models would come with LTE though so it's possible they included the chips in all devices and turned them off for GPS only models, like you mentioned originally.

Interesting point to mention, but the difference in weight is so small that it won't make much of an impact.