Sometimes will have similar masses, sometimes will have much different masses. In extreme cases, can have the lower mass star be something like a brown dwarf , an object with not quite enough mass to become a star. Remember that we can estimate masses of stars if they're in binaries. Some of the activity of star formation can be violent . Sometimes jets will run into material around the protostar and snowplow it up and produce Herbig-Haro objects .
Collision generates energy, get emission from gas blobs.
Sometimes see both jets but many times the jet going away from us is hidden by the protostellar disk. Causes of jets are still being worked on but it seems clear that both magnetic fields and the energy of the protostar drives them. The winds and jets will clear out material from the polar regions of the star so that we can get views of the star in visible light if we're lucky enough to have one of the star's poles pointing at us. When nuclear fusion begins, the protostar becomes a star. Core temperature needs to be 10 million K, kicks off the proton-proton chain.