A System bet allows players to bet on multiple events and outcomes, removing the all or nothing approach to Parlay Bets. That means part of your System Bet can win even if others lose. The trade-off is that System Bets come at a greater expense because they increase the total number of picks in your bet.
The main difference between system bets and multi (parlay) bets is that you can win a system bet even if not all your picks are correct. For example, in the case of a 2/3 system bet, you win even if only two of your three predictions turn out to be correct.