Question

How is fragmentation different from fertilization?

Answer 1

Reproduction by fragmentation may occur when (or rather if) a fragment (piece) of an organism can give rise to a new organism of the same species.
See http://en.wikipedia.org/wiki/Fragmentation_(reproduction)

Planaria (a flatworm species) are famous for their ability to regenerate if divided by cuts across their bodies. Experiments show that, in fragments that do not already have a head, a new head grows most quickly on those closest to the original head
- see http://en.wikipedia.org/wiki/Flatworm

Answer 2

in short and v.major difference is that in fertiliztion there is a need of gametes while in fragmentation no need of gametes