Because they are different govs, with different agendas, each of them see the propaganda of others as evil, but it's still all very much propaganda.
Remember CNN diffused many bits on how WMD were in Irak to justify the war the UN voted against. The USA went to war anyway, and we learned there were no WMD.
Al Jazeera does the same, but for their side.
It is, nevertheless, quite qualitative content for many topics, and give you another points of on the world events than our own medias outlet.