We know what full enlightenment actually is can’t be talked about since it isn’t anything of our world, but we can atleast have an estimation of the path there. There’s alot of argument about liberation and it’s “stages”, and in the suttas it can be pretty confusing. Especially when things like the pavarana sutta and similar ones to it seem to even describe different vehicles of liberation.
To begin this I believe a look at jhana is necessary.
Jhana jhana jhana. And jhana again. What the sam hell is jhana?
Jhana has a prerequisite-morality. It’s the beginning of the path, it seems the reason for this is not only simply because it’s the right thing to do but because without adherence to the minimum of the five precepts, entry way into jhana is exceedingly difficult (if not impossible). I cite here AN 10.1, DN 10 as examples for morality as prerequisite.
Ignoring interpretations on the correctness of the depth of jhana, what we know about jhana reading back from the suttas is that they’re states of mental absorption (of some degree) which have a pleasure not deriving from tanha or worldly sensual input. I cite as an example of the wholesomeness of jhana AN 3.63
This would mean that any correct mindfulness and it’s fruit of jhana would need to be born from the bare bones of morality at minimum, and the marker for jhana absorption would be the inherently unworldly pleasure born of seclusion. The pleasure of jhana inherently inturn also secludes the mind from the hindrances. Going further we could safely deduce that the hindrances are the basis of wrong mindfulness and wrong view, as they are inherently entwined with ignorance and thus craving. I cite as example Samyutta Nikaya XLV.1
We can deduce from this then that statements such as Ajahn Brahm’s that jhana is a state of/arises from letting go, is correct.
Naturally then jhana is entangled with insight due to the fact it naturally involves proper seclusion from the hindrances. I cite as examples AN 10.7 AN 9.36 Dhammapada 372 and again Samyutta Nikaya XLV.1
Long story short jhanas are states of letting go more or less, great! So, how do we deal with different ways of liberation?
Simple; the differences in liberation through either insight or absorption is superficial. Much in the same way that buddha taught in different ways to different people dependent on what was most suitable for them, while it all still being dhamma, the liberation described is in truth born of what is most suitable at the time to the mind of the disciple.
Instead of the stages of enlightenment being a gradual process of achievements you go through, they’re like jhana. They’re states of letting go, but with permanency. the pavarana sutta and it’s ilk then instead what factor of enlightenment sparks the ability for them to let go permanently.
I cite AN 5.51 DN 29,25 AN 3.85 AN 3.86 MN 111
TLDR; the stages of enlightenment aren’t neccesarily stages, they’re just the degree to which someone was able to cultivate the factors of enlightenment and subsequent annihilation of fetters.