yea i do find adler a little less variant in his playing style, although IMO i wont say that sweet child and welcome to the jungle are very similiar cuz the intro part of the song where he hits the snare/tom, snare/BD, snare/tom/bd however u play it part is meant to go with the strumming of the guitar, and i like the fact that he kept things simple and sweet
sorum on the other hand, id have to say techniquely better, although some dont like what he did to the band accusing him of turning it into a heavy metal band, id say his playing fits the songs very well indeed, i especially like his style for the song slither (although from VR but still teh same guy drumming with the same bassist and lead guit)
but honestly i wouldnt say that any of the drummer played a very huge part in GNR's success, when u think of great drummers, does adler or sorum come to u mind very easily? well not to mine... but in the case of say slash (though ppl call him overrated), duff, they are household names in their music field (of course if ur not a rock listener then dif story la haha)... though im not saying that they didnt play a part in the band