Ramana Maharshi says There are grades only in the experience of the jiva and not in Reality

Devotee: “There must be stages of progress for gaining the Absolute. Are there grades of Reality?”

Bhagavan: “There are no grades of Reality. There are grades in the experience of the jiva.”

Note: “Grades of Reality?” Reality is perfect because it is partless, integral, and changeless, or else it contradicts itself.So, Reality is not affected by evolution, nor is it divisible into a number of imperfect beings who need the evolution to attain perfection. We have seen elsewhere that the jiva is the Self itself, but deluded.

The appearance of multiplicity of jivas is an illusion due to the unfoldment of the senses which create qualities and hence differences. Bhagavan says that it is not the Self that has grades but the experiences of the jivas. Thus the difference between the savage and the Jnani is one of experience, that is, of mental outlooks and not of substance — of being.

Devotee: “There is a multiplicity of jivas. Jivas are certainly many.”

Bhagavan: “Jiva is called so because he sees the world. A dreamer sees many jivas in dream, but all of them are not real. The dreamer alone exists and he sees all. So it is with the individuals and the world.”

Note: The critics argue that if the world is the senses, as Vedanta says, individual senses would show exclusively individual worlds, so that there would be as many worlds as there are human beings with no connection with one another,which experience disproves.

Bhagavan answers that all the senses, all the men and all the worlds are the dreams or thoughts of the jiva, which alone exists as the dreamer or thinker. As the jiva in dream sees other jivas with bodies and senses, without any of them enjoying real existence, so it does in the waking state (jagrat).

Jagrat is called waking only in comparison with the dream state known to us, because the senses are then all out to intensify the illusion of a real external world, whereas the dream state feeds on mere impressions carried over from the state of jagrat, and not on the senses, which are then withdrawn.

Source: REFLECTIONS ON TALKS WITH SRI RAMANA MAHARSHI By S.S. COHEN

My Spiritual Friends Subramanian and Udai garu wants to add few points

Yes. Reality is only One and partless and without differences.

Kaivalya Navaneetam however says that there are 7 Jnana Bhoomis, the Lands of Wisdom.

And there are 4 types of Jivan Muktas.

The Sadhakas reach subeccha, vicharana and dhanumansi. They
are not Jivan Muktas. They attain heaven and some posts like
Indra and then come back to earth to pursue their sadhana.

The one who reaches the fourth stage, is Brahmavid.
The one who reaches the fifth stage, is Brahmavidvara,
The one who reaches the sixth stage, is Brahmavidavariya.
The one who reaches the seventh state is, Brahmavidvarishta.

The fourth stage is called Sattvapatti. The fifth is Asamsatti,
the sixth is Pathartha bhavana, he seventh is Turiya.

(Kaivalya Navaneetam, Verses 255-257).

Udai garu says,

Essentially one who knows that he is Consciousness can be said to have the knowledge.
But if it gets limited to the mind and he or she is not able to remain totally detached due to vasanas, they live like ordinary humans. But in such cases, the vasanas will eventually dissolve.and as the vasanas dissolve they gain conviction that they are Consciousness and start owning it up.

The process is slow. And i think it cannot be forced to happen fast.As Kabir says:

Dheere Dheere re mana. Dheere sab kuch hoye [Slowly, Slowly oh mind! Slowly everything happens].Maali seenche sau ghada , ritu aye phal hoye kabira, rithu aye phal hoye [The garder may water the plant with 100 pots of water.but it will give fruits only when its season].

With spiritual practice also, one has to allow things to happen ... slowly, but without stopping, one should start to remain as Self.