Hmmm... just writing from my understanding only. Not
definitive.
For jhana meditation, it is a kind of concentration. Your mind
fixate on a object. When one get out of the meditation, the jhana
states goes away. With Jhana meditation, insight may not
necessarily arise. I did jhana meditation since 1985 and have since
stop after realising that it did not produce any results towards
enlightenment (for me). Also, in the jhana states, the workings of
the self is not understood. There is always an observer (self)
watching the changes of states. Also, the various systems have
different ways of assessing the jhanas and they do not tally with
one another.
From my understanding, vipassana brings about awareness and
mindfulness. However, it is working largely and initially at the
mental level. The mind mentally notes whatever is occuring.
From my understanding self-liberation (in Dzogchen) is working
at a different level from Vipassana. It can only occur after going
deep into and stabilizing firmly in no-self state. I am not at the
self-liberation level so I can only speculate. My understanding is
that arhats MAY NOT necessarily understand self-liberation. It is
the stages beyond arhatship because it is working at levels that is
not mental at all. The liberation is automatic without the arising
of the 'self'. At the vipassana level, the mindfulness practice is
at the mental level. In another word, the mental noting is through
the 'observer self'. A grasping (in the form of a subtle self) is
doing the mental noting in the case of vipassana. The depth is
different.
Note... I am not an arhat. I am making some assumptions
here.
Just my opinion only.
Actually Theravadin insight meditation isn't look from the
perspective of an observer, but nevertheless there are differences
with the Dzogchen system of practice.
http://www.berzinarchives.com/web/en/archives/advanced/dzogchen/basic_points/introduction_dzogchen.html#n14882cdba2d9db0c6
Vipassana (lhag-mthong, Skt.
vipashyana) meditation within the sphere of Theravada
Buddhism entails noting and watching the arising and falling of
moments of conceptual thinking, but not through the “eyes” of an
independently existing “me” as the observer. Through this
procedure, we realize the impermanence or fleeting nature of
conceptual thought and of mental activity in general. We also
realize that mental activity occurs without an independent agent
“me” either observing it or making it happen.
Dzogchen meditation, in contrast, focuses
on the simultaneous arising, abiding, and disappearing of moments
of conceptual thinking – not simply noting or watching it. This
allows us to recognize first effulgent rigpa – the aspect of rigpa
that spontaneously establishes the appearance of simultaneously
arising, abiding, and disappearing thoughts. It then allows us to
recognize essence rigpa – the aspect of rigpa that serves as the
cognitive space underlying every moment of mental activity and
allowing for the spontaneous establishment of simultaneously
arising, abiding, and disappearing thoughts.
Moreover, vipassana deals only with the grosser levels of mental
activity, whereas dzogchen accesses the subtlest level, rigpa.