In some cases one can write either в тазе/в тазу...на мысе/на мысу...в снегу/в снеге... и.т.д.
Is there a difference in meaning between the old locative case (у,ю endings) and the prepositional case?
In some cases one can write either в тазе/в тазу...на мысе/на мысу...в снегу/в снеге... и.т.д.
Is there a difference in meaning between the old locative case (у,ю endings) and the prepositional case?
It's quite hard to argue on this. But I can say that my personal preference is to use the locative as much as possible, reverting to the prepositional case only if the sentence has absolutely nothing to do with "physical location."
Yet there are some nouns that I never use in the locative. For example, I never say "на мысу" — only "на мысе."
Perhaps, what one is used to saying is more important here than some bookish rules.
The difference in meaning is only evident in a relatively small group of nouns:
These words have a clear distinction between the locative and the prepositional: using one instead of the other will sound ungrammatical to most native speakers: *гулять в саде, *разочароваться в Крыму.
The second group is comprised of words that are gradually losing said distinction:
Such words allow the use of the prepositional form in place of the locative form (but not vice-versa): на дубе / на дубу, в стоге / в стогу, на счёте / на счету.
Some of these words have only lost the distinction in some of their meanings while retaining it in other meanings, e.g. строй (социальный, музыкальный vs военный), круг (фигура vs общность), угол (angle vs corner).
На дому effectively became an adverb (vs на доме).
The third and largest group is comprised of words which lost or never had the distinction. Using the -у form with them will sound odd. E.g. in 1920-1950s it used to be correct to say "в отпуску" but these days, you're bound to raise some eyebrows if you dare to use this expression.
Related StackExchange questions:
The short answer is no, in some constructions/phrases you use the former, in others you use the latter form. Also, many nouns don't have a separate locative form. Here's an article that argues that the usage of the locative case signals a full, intensive contact where the position of the object is strictly determined, or its freedom of movement is limited, or its nature is partially or fully changed. Still, this is of little practical value. In every Preposition + Noun phrase, you have to know exacty which form of the noun is to be used.
The difference between the two really does exist. It's a bit hard to describe, but I'll give you a couple of examples of instances where both options sound correct. It's not a strict rule, but I hope it will help you to get the hang of it.
When you say something is "в снегу", it means that the object is surrounded by snow. It has a close relationship with the snow, but it is not a part of the snow. Example: "У нас до конца марта деревья в негу стоят."
But when you say that something is "в снеге", it means that the object is a part of the snow itself. This is generally used when some of the properties of the snow itself as a substance are made up by the object in question. Example: "В городском снеге всегда полно цементной пыли."