36 for 0!! Okay!!
Carla, sometimes, you know, you shove too much stuff in the cupboard in your bedroom, and then, the next time you open the cupboard, all this stuff just falls all over the floor. Well, your question is a very good question, but it is one of those questions that opens the cupboard, and stuff falls all over the floor . . .
Here is a very very simple answer. You have a think about it, then you might like to ask another question here on the forum:
The answer is: you really need to learn these two, and others like them, one by one, the same way that you learn idioms. The reason is that both-prepositions-and-their-meanings tend to 'wander around.' That is, maybe one hundred years ago we said, 'They verb-X preposition-Y him,' but now we say, 'They verb-X prepositon-L him' – but the two sentences mean exactly the same thing. (Look up the term 'collocation.')
I teach my students thus:
Some prepositions are 'literal.' Some prepositions are not: 'She sat ON the horse,' 'She sat NEAR the horse,' 'She sat UNDER the horse [which is a bit scary],' 'She sat BEHIND the horse [which is even scarier].' In each of these sentences, the preposition is 'literal,' meaning that it does indeed give you information about the position of 'she.' However, in sentences like, 'May he rest in peace,' and 'She felt at peace,' the situation is: in English (in all languages) we make 'strings' of words. For example: 'Word A + Word B + Word C.' Together, these three words have Meaning 'Y.' The meanings of the different words in the string do not necessarily relate to the meaning of the whole string – and that is exactly what an idiom is!! A certain string of words is What We Say in English. All English speakers know what that string of words means. You must learn the meaning that goes with each string.
So, try to guess which prepositions are 'literal'; and learn the others one by one, the same way that you learn idioms and collocations.
Finally, Carla, some encouragement: yes, this issue is a difficult issue. However, if you work hard at it, your English will eventually be much much more fluent than the English of almost all other students.
Rocky Gully, Western Australia
Student or Learner