I have never been able to spot the difference between throw and toss.
For instance, both of these sentences make perfect sense to me:
He is going to toss a rock at you.
He is going to throw a rock at you.
How should I know when to use one or the other?
Best Answer
Toss has a more casual, lighter, connotation than throw which is a more powerful and deliberate action.
One tosses a towel to one's club mate in the dressing room, but out on the field of play one throws the ball hard in from the boundary.
Toss to me always suggests an underarm movement, whilst throw involves the full overarm action.
This is only an approximate answer to the question and there are no hard and fast rules. You may well hear usages which do not conform exactly to what I have said.
Toss also has some sexual and slang connotations but no point in going into those here.