Convergent plate boundaries caused by regional compressional tectonic forces like but divergent plate boundaries caused by tensile tectonic forces.
Convergent plate boundaries are associated by subduction zones where high density oceanic plate sink under light continental plate or younger oceanic plate and characterized by generation of long chains of inland volcanoes parallel to continental shelf called volcanic arc like Andes volcanic mountain range that in case of oceanic-continental convergence but in case of oceanic-oceanic convergence that will create an island arc (chain of volcanic islands into the ocean) like Philippine Islands.
These volcanoes formed by continuous continuous supply of magma which generated by partial melting of subducted oceanic plate. Eventually Continental-continental convergence that will cause continental collision whereby the subduction zone is destroyed, mountains produced, and two continents sutured together like Himalayas mountain system.
Divergent boundaries are initiated by continental rifting processes and formation of growing ocean basin. Divergent boundaries are characterized by plates move apart to produce gaps which molten basaltic lava rises to fill.