Trust/Believe : “信任” vs “相信”
I'm not a native Chinese speaker but I've always used 相信 to mean believe (related to truth/falsity) and 信任 to mean trust/confidence (related to success/failure).
我相信你 I believe you. I believe what you just said. I think you are telling the truth. I don't think you are lying.
我信任你 I trust you. I trust in your ability. I have faith in you. You won't let me or yourself down. I am confident that you will succeed. I am confident that you will not fail.