"The girl drinks the coffee, the milk or the tea."
Translation:Fata bea cafeaua, laptele sau ceaiul.
They're quite subtle.
This is mostly based on my own observations, so don't take it as the hard truth:
I would say that "sau" is more common in the usual usage.
Do you want apples or oranges? - Vrei mere sau portocale? ("ori" would work here, but "sau" feels more natural).
It's also more common used in contexts in which it could mean "și":
Lions can be found in the jungle, at the circus, or in a zoo. - Leii se găsesc în junglă, la circ sau la zoo.
"Sau" is also used exclusively for explanations (meaning "in other words"):
"The hobbit, or there and back again" - "Hobbitul, sau până acolo și înapoi"
"Ori" is more common in cases corresponding to the "either... or..." construct in English:
You either come with me or you stay at home. - Ori vii cu mine, ori rămâi acasă.
We can meet either on Monday or on Thursday. - Ne putem întâlni ori luni, ori joi.
("sau" would work in these examples, but "ori" feels more natural.)
Note that there is also "fie", which can be used instead of "ori", but only in sentences like the last examples.
You either come with me or you stay at home. - Fie vii cu mine, fie rămâi acasă.
Do you want apples or oranges? - Vrei mere fie portocale?
It's worth mentioning that "ori" has other unrelated meanings, such as "times":
Two times four is eight. - Doi ori patru e opt.
I've been here six times. - Am fost aici de șase ori.
(it's a bit weird how these correspond, seeing as they mean different things both in Romanian and in English).
Finally, the word "or" also exists in Romanian, but it has a different meaning than above. (although a lot of native speakers confuse it with "ori").
* the official Romanian translation of the title is just "Hobbitul", but I couldn't think of any other example, sorry :)
Exactly what I'd been wondering about - thanks for the thorough explanation!
A question on "ori", given the last bit of your response: since there are [at least] two distinct senses of the word, might they have different roots, like bow (the front end of a ship) and bow (to bend one's body over)?