I tend to view Wilson and Roosevelt as a far more upper-class, intellectual brand of liberalism, though obviously one still oriented towards helping the "common man". Bryan was much more down-to-earth in that sense. As well, Wilson and Roosevelt were of the a more urban "progressive" background while Bryan was of the "populist" orientation. Though one sort of preceded/worked alongside/was counterpart to the other, there's a divide, IMO. Although, if it weren't for Byan's endorsement at the 1912 DNC, it's unlikely that Wilson would have even been nominated.
Bryan's youth probably helped him in some areas with "common man".