From a quick google search: "Jam" can't be called jam when it doesn't meet the legal definition of jam, which typically means it contains too little fruit, has large chunks of fruit making it more like a preserve, or includes added ingredients like nuts or large pieces of fruit peel that would classify it as a conserve, rather than a pure jam.
It's not been labelled a preserve or conserve so it must be because it doesn't contain enough fruit.