What is the difference between the processes of allopatric and sympatric speciation?

Sympatric speciation is associated with the divergence of groups of individuals of the same species and those living in the same area according to ecological characteristics. In this case, individuals with intermediate characteristics turn out to be less adapted. Diverging groups form new species. A feature of the sympatric pathway of speciation is that it leads to the emergence of new species, always morphologically close to the original species. Only in the case of the hybridogenic appearance of species does a new species form appear, different from each of the parental ones.
Allopatric speciation is caused by the division of the species range into several isolated parts. The emergence of geographical barriers (mountain ranges, sea straits, etc.) leads to the emergence of isolates – geographically isolated populations. Interruption of gene flow between isolates, on the one hand, and the action of natural selection, on the other, lead to their reproductive isolation and the formation of independent species.