On the left we have a Philips son-t 70W bulb and in the right one osram vialox nav(son)-t 70W. Why is the light bulb philips thinner and the osram is of normal size for a 70W?
You can also see that,after a lot of use, at Philips, a black spot appeared in the middle, I think because the walls of the outer glass are too close to the burner. Just philips made small diameter bulbs like this one or other manufacturers too?
Also, can you tell me the date of manufacture because I do not know the codes, at philips write: "0H" and at osram write: "T 158"

I would ratner guess the exact bulb size and shape is arbitrary for each maker, what is standardized is just the relative positions of the arctube vs the socket. So each maker uses what is more convenient and cheaper for the production. This also depends to big extend to what other products are sharing the same production line (narrower tube saves some material so it may be cheaper if only this lamp is made on that line, but retooling when alternating with higher wattage products when sharing the line may be more expensive than the savings from the less material usage).

The darkening on the Philips lamp is not related to the operating temperature of the glass, but to the arctube failure (leaking Na, which reacts with the glass into that brownish tint), so I very strongly doubt it is related in any way with the outer tube diameter.

I had and I saw many burned bulbs or near the end of life, very worn, but none made this brownish stain, that's why I guess guilty is the distance from the burner to the glass, you might be right and be leakage undetectable with the human eye.

The leak is possible to recognize only via such stain formation, we are talking about very tiny amount of sodium, it leaked as a gas and so slowly it haven't formed significant discharge in the outer (then the tube would be completely black or even heat shattered).

And yes, it is not a normal EOL for a HPS, but rather a defect in the arctube, so vast majority of lamps does never reach that state.

But I would say it is not that uncommon defect, have seen not that many lamps as a few people here (who are doing maintenance of some lighting as their job), but have seen already a few such failure. They were early faikures, so way before the lamp life was due...