Both ‘ some’ and ‘any’ are used to refer to indefinite quantities, i.e., when it is not necessary to specify a number. For example, ‘I would like some milk’ indicates that the speaker wants milk, but it is not stated how much of it he or she wants. Similarly, ‘Is there any cake left?’ does not specify how much cake the speaker wants there to be; any amount will do for the purpose of the question. There are important differences between the two that must be grasped for usage, however.
‘ Some’ is commonly used in affirmative statements, such as I would like to have some fun.
‘ Any’ is hardly ever used in such statements, except to emphasise that the quality of the object does not matter. For example,‘I would like any apples’ suggests that the speaker does not care what kind of apples they are (indicating a desperate need or desire for apples), whereas‘ I would like some apples’does not suggest anything about the quality of the apples or desperation of the speaker.
‘ Any’ is commonly used in negative statements, such as‘We do not have any apples.’ Here, ‘some’ may not be used.
‘ Any’ is also used in affirmative statements, if the statements contain negative words such as ‘hardly’, ‘barely’, ‘never’, ‘without’, ‘little’, etc. For example,‘ We hardly have any apples’ cannot be rewritten as‘We hardly have some apples.’
While both ‘any’ and ‘some’ can be used in questions, ‘any’ is more common and natural in this form.
‘ Do you have any apples?’can be rewritten as‘Do you have some apples?’However, ‘ some’ is not always applicable. For example, in the case of‘ Do you have any idea what the score is?’, ‘ any’ cannot be replaced by ‘some’.
‘ Some’ is more commonly used in offers and requests, such as Would you like some tea?
Both ‘ some’ and ‘ any are common in ‘ if’ clauses, with similar meanings, as in‘ If you need some/any assistance, feel free to give me a ring.’