A reminder is to bring something to your mind again.
"It's the end of the month, remember to turn in your reports."
Advice is a suggestion about how you should do something or live your life.
"You should give up on being an actor and get a real career."
"If it floats or flies, rent, don't buy."
Most people don't mind being reminded of something they wanted to remember or do. Most don't like being told what to do or how to live their life, especially if the advice is unsolicited.
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