politics is more about the system from what i've seen (so how politics, voting, parties etc. are structured) whereas sociology is about people - how they act and why they act that way. i'd advise looking at the syllabus for both, making sure you're looking at the right exam board, to see which seems more interesting to you. i'd say they'd both be good for law and journalism and which is better depends on the kind of journalism/law you want to do.