juggernaut doesnt breathe, or eat. i doubt supeerman could physically harm him, but even if he managed it juggernaut heals pretty much instantly. he had all his flesh and organs torn from his body mysticlly once and kept going, so he doesnt even need lungs. or a brain, or heart, or anything else.
i dont know where you get the idea superman is that much stronger, juggernauts strength is supposed to be limitless, he doesnt have as many feats as superman, but if you count the amount of comics hes been in in comparison to superman its not hard to see why.
juggernaut is pretty much the ultimate physical force, unstoppable and invincible, but thats all he has going for him. no speed or ranged attacks. without telepathy of mystic power he cant really be beaten. superman is supposed to be weak against magic, juggernaut is mystical. his forcefield is mystical in origin so superman might not be able to get through it.
i dont know as much about superman as i do juggernaut, but if all superman brings is physical force and heat beams i dont see that he can do much. juggernaut has taken thors godforce and stood there unharmed. he even tried walked against it but the ground caved. so not only did he survive it, it either caused him little damage, or no damage.
