I feel like there is a tiny difference between those two, but I didn't manage to figure out what was the difference. Both translates to "calibration".
The definition of "étalonner" in the TLFi specifies that this is a procedure that enables one to verify the accuracy of a means of measurement against a standard ("l'étalon") and to make notches or marks on that instrument so as to confirm that it corresponds to the true value (that given by the standard); this second part of the process is a matter of law.
(TLFi) A. Vérifier une mesure en la comparant à l'étalon et la poinçonner pour attester sa conformité légale. Étalonner des poids, des mesures.
"Calibrer" describes the same process less the legal part and taking into account that the verification involves machining or manipulations that are proper only to the object considered for "calibrage" and through which that object acquires the desired dimensions.
(TLFi) B. Donner le calibre, les dimensions voulues à un objet.
There exists then a slight analogy between the two processes : (étalon ↔ instrument), (instrument ↔ object); moreover, the relation of "transitivity" in these processes ensures that the dimensions of the object are given in number of units all equal to that of the standard.
It is useful to have a more precise idea of what is a standard in the domain of measurement;
(TLFi, étalon²) ("standard") A. MÉTROL. Modèle de poids ou de mesure, appareil établi avec une extrême précision et sous l'autorité et la garantie de l'État, qui sert de référence pour les autres mesures ou appareils de poids et mesures.
Incidentally, we see in this definition that an "étalon" and an "instrument" are considered to be both "appareils" (apparatuses), so much for the analogy.
For quite some time now, the standards are not established solely through the authority of the individual states, but also through that which an international agreement makes bear on the matter, the main international body governing this process being the International Bureau of Weights and Measures (BIPM);
(ref) International Bureau of Weights and Measures (BIPM), French : "Bureau International des Poids et Mesures", international organization founded to bring about the unification of measurement systems, to establish and preserve fundamental international standards and prototypes, to verify national standards, and to determine fundamental physical constants. The bureau was established by a convention signed in Paris on May 20, 1875, effective January 1876. In 1921 a modified convention was signed.
Calibrer comes from calibre which is commonly used to refer to the diameter of an ammunition like a cannonball or a bullet (English: caliber/calibre) or anything that can be sorted by its diameter by passing it though reference holes.
For example, some fruits are often calibrés by using oscillating panels with holes of different sizes, increasing from the beginning to the end. The calibre might also be based on the weight instead of a diameter/size, like with eggs.
The calibrage then consists to sort out elements of a same kind by size, with the constraint that for one element to be of a given caliber, it must be able to pass through the hole. It might be smaller but shouldn't be smaller than the previous caliber diameter.
On the other hand, étalonner comes from étalon which is a measurement unit used to serve as a reference for other measurement devices to avoid discrepancy. An example of such an étalon was the mètre étalon en platine iridié which used to be the metric system length reference standard between 1927 and 1960.
Étalonner is to make sure a measuring instrument closely matches the reference one. Unlike with the calibrage, during an étalonnage, the measurement must not be inferior or equal to the reference but the difference (positive or negative) must be less than the accepted error margin, typically very small. Because it sounds like a French word and has no pronunciation issues, the term calibration is sometimes used as is in French in contexts where étalonnage would have been appropriate.
To summarize, a calibre is more a range belonging to a set of increasing size of calibres and specific to objects of a kind while an étalon is a single generic reference, a standard.
Both calibrer and étalonner mean to compare something with a reference object, but the former applies more to final objects which usually stay unaffected by the process while the second applies to other reference objects that will be used themselves later as étalons too, so can be modified (i.e. adjusted) in the process to match the étalon.
Calibrer is definitely not a subset of étalonner. They apply to different objects.
See also (Wikipedia):
Good question, the difference is very subtle. If I go on the english Wikipedia page for "Etalonnage", it sends me to "Calibration" page. But you're right, there is indeed a difference between these two words.
From my point of view, and from what I learned in physics class :
"étalonner" states that you compare your result to a standard, an indicator.
It is different from "calibrer" which does not necessarily require comparison with a value. A synonym of calibrer can be ajuster
Complément aux réponses :
Je ne sais pas si tu es à l'aise avec la lecture de textes français. Si c'est le cas :
Voici quelques extraits :
Les confusions calibrage/calibration/étalonnage viennent certainement du fait que le mot anglais équivalent à étalonnage est "calibration"... facile à franciser en calibration et à déformer en calibrage.
Beaucoup d'équipements de laboratoire possèdent ainsi une fonction de "calibration" qui est évidemment déstinée aux étalonnages. finalement, pas de quoi casser 4 pattes pattes à un canard.
Selon le vocabulaire de métrologie (VIM), le calibrage d'un instrument de mesure ne doit pas être confondu avec l'étalonnage (le mot anglais pour calibrage est gauging)! Le calibrage, c'est le positionnement matériel de chaque repère (éventuellement de certains repères principaux seulement) d'un instrument de mesure en fonction de la valeur correspondante du mesurande.
Un thread scientifique intéressant :
Et un thread du point de vue de la traduction
Bien sûr, il y une pléthore de liens pertinents parce qu'il s'agit d'une question récurrente. On peut les retrouver en gouglant "étalonner vs calibrer" par exemple.