i guess
limitless, nothingness, emptiness and signless are the 4 arupa jhanas. It seem arupa jhanas are about awareness release. Fulfilling resolve, hearts desire.
https://accesstoinsight.org/tipitaka/mn ... .than.html
"Furthermore, there is the case where an individual, out of conviction, goes forth from the home life into homelessness, (thinking,) 'I am beset by birth, by aging-&-death, by sorrows, lamentations, pains, distresses, & despairs, beset by stress, overcome with stress. Perhaps the end of this entire mass of stress might be discerned!' Having thus gone forth, he encounters gain, offerings, & fame. He is not gratified with that gain, offerings, & fame, his resolve not fulfilled. Because of that gain, offerings, & fame he does not exalt himself or disparage others. He generates desire & exerts himself for the realization of those qualities that are higher & more sublime than gain, offerings, & fame. He is not drooping or lax. He achieves consummation in virtue. He is gratified with that consummation in virtue, but his resolve is not fulfilled. Because of that consummation in virtue does not exalt himself or disparage others. He generates desire & exerts himself for the realization of those qualities that are higher & more sublime than consummation in virtue. He is not drooping or lax. He achieves consummation in concentration. He is gratified with that consummation in concentration, but his resolve is not fulfilled. Because of that consummation in concentration he does not exalt himself or disparage others. He generates desire & exerts himself for the realization of those qualities that are higher & more sublime than consummation in concentration. He is not drooping or lax. He achieves knowledge & vision. He is gratified with that knowledge & vision, but his resolve is not fulfilled. Because of that knowledge & vision he does not himself or disparage others. He generates desire & exerts himself for the realization of those qualities that are higher & more sublime than knowledge & vision. He is not drooping or lax.
"And which, brahman, are the qualities that are higher & more sublime than knowledge & vision?
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list of jhanas
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and then,
"These are the qualities higher & more sublime than knowledge & vision.
"Just like the man who, in need of heartwood, seeking heartwood, wandering in search of heartwood, cutting away just the heartwood of a great standing tree possessed of heartwood, went off carrying it, knowing, 'heartwood': Whatever heartwood-business he had with heartwood, his purpose will be served. This individual, I tell you, is similar to that.
"Brahman, this holy life doesn't have as its reward gain, offerings, & fame, doesn't have as its reward consummation of virtue, doesn't have as its reward consummation of concentration, doesn't have as its reward knowledge & vision, but the unprovoked [3] awareness-release: That is the purpose of this holy life, that is its heartwood, that its final end."
Difference is 1,2,3..8 jhana conditions(non-conditions). Getting more sublime ..