The difference between peach jelly, jam, and preserves is the amounts of sugar used. Jams have a higher sugar content than jellies, which makes them softer and stickier. Preserves are not as sweet as jams or jelly because the sugar is boiled with fruit during the cooking process to make it more natural for your body's digestive system. Always remember this, jelly is made from the juices of the fruit. Preserves are made from whole pieces of fruit, and jam is the middle child with pieces of fruit in fruit juice.