On The Walking Dead, there wasn’t a major separation of characters until Andrea and Michonne were kidnapped by Merle and taken to Woodbury in the third season. There wasn’t another major separation until the fourth season, when Rick expelled Carol from the group for killing Karen and David. On The Walking Dead, the characters wanted to be together; they were motivated to be together. They still are. With the exception of Rick, Carl, and Judith, there are no family bonds keeping the characters in The Walking Dead together: They have created their own family, so much so that even when they are separated, the bond still exists.
The bond that glues the characters together on Fear the Walking Dead, conversely, is thin and tenuous, even among groups of families. It took these characters most of the first season to find each other, but the calamities they have faced together aren’t strengthening their bond as a unit. By the midseason finale of the second season, the group had already splintered: Chris and Travis went one way; Nick went another; a badly burned Daniel roamed; and Alicia, Madison, Ofelia and Victor went yet another way. It wasn’t long, however, before Ofelia turned around and abandoned Victor and the Clarks.