The word some refers to an unspecified number or amount of an object. Are some difficulty and some difficulties both grammatical? If so, do they mean the same thing or two different things?
Both are grammatical. They are used in different circumstances.
Some difficulty is a reference to an unquantifiable problem.
He had some difficulty in learning to drive.
In contrast, some difficulties is a reference to a number of problems that are being aggregated.
He has had some difficulties lately, with the death of his mother, the loss of his job and the cancellation of his favorite television show.