I'm having a lot of trouble remember the difference between these. Come to think of it I can't figure out what the difference is!

Anyone have any tips for separating these two in both meaning and writing?

Thanks!

A good way to think of it is this:

広辞苑 Wrote:不{副}…ず。下のことばを打ち消す否定詞
否{形}ある性質の逆の面を意味することば。

不 cancels out what comes after
否 reverses the meaning (of what comes after/it's attached to)

Those two meanings obviously overlap somewhat. You can see that they are also different parts of speech (形容詞 vs 副詞）.

... not sure. One's used in one word, won isn't?
不可能 (impossible)
不利 (disadvantage)

拒否 (to be rejected, to refuse)
否定 (denial)

I can't think of any compound words where 不 is the last kanji, but I'm going to guess that this is because in Chinese, you add the negation in front of the word you want to negate.
(我是美国人，我不是中国人。
我(I)是(am/is)美国(USA)人(person)，我(I)不(not)是(am/is)中国(China)人(Person))

Unfortunately, 不 vs. 無 vs. 非 vs. 否 is a tough topic. I think it's even tough for native Japanese because I remember seeing in some kanken materials a section where you had to choose the right one for the opposites of various words.

Since this is in the RTK1 section I assume you're having trouble keeping the keywords apart; I don't know if this is particularly important. 不 is never used alone (at least in modern Japanese), and 否 is used alone only rarely (as a strange kanji for いや, or in the expression ...か否か). So you basically just have to learn what words they appear in, and you'll never see a case (AFAIK) where you have 不 + some kanji meaning one thing, and 否 + some kanji meaning a totally different thing.

Quote:I can't think of any compound words where 不 is the last kanji,

I don't think there are any, and I agree with your reason why.