Seeing as someone who merely touches a Neveilah becomes Tamei, why does the Torah need to teach (verse 26) about one who carries it?
Rashi: Because one who touches is not Metamei the clothes that he is wearing, whereas one who carries is Metamei them. 1
Bechor Shor (28): One who carries becomes Tamei even if he did not touch it. Rashbam (28) - this is only if he moved it, but not if another put a Neveilah on his shoulder and he did not move..
See Ramban DH 'v'Hizkir'.