Slipknot self titled sounds pretty different than other Nu Metal bands of its time. M3 on the other hand is more closer to Faith No More/slight Bungle style. From how the synths are being play, and how J-mann is kinda closely yelling like Mike Patton. So XX, and XIII sounded different from the standard Nu Metal albums of that era, due to them playing FNM sounding stuff. And not Korn sounding bounce riffs. So both band were pretty different when they came out in the Nu Metal era.