I wish I could understand Japanese

Homophones are even worse in Chinese, as every character has only one syllable, whereas some Kanji words have multiple syllables. For example, 私 is "si" in Mandarin, but it is "watashi" in Japanese? As stated before, the context of the conversation is crucial to understanding.

*wishes Chinese was easier to learn >:[*

And, I'm just wondering... In Japanese, what's the difference between 私 and 我?