What is that highest truth (tattvam)? This verse explains. It is advaya-jnanam. And what is jnanam? It is called brahman. What the jnanis call brahman is jnanam. According to them it is without form, without distinction of knower and known, a condition of consciousness alone.

This jnanam is called Paramatma by the yogis. This jnanam is advaitam because of oneness between him and his saktis--jiva and prakrti, because as cause he pervades the effect, this universe, the prison-like abode, and because Paramatma is non-different from his form and abodes through particularization of his consciousness aspect. According to the yogis, the form of Paramatma is still pure jnana because his form is also the same knowledge. Even though he is pure jnana, Paramatma is also the shelter of particularization of jnana, because he performs functions such as acting as the witness. Paramatma is just like the sun or a lamp. Though the sun is the very form of light, it is also the possessor of luminosity. Thus there is no contradiction. Paramatma is understood to have a form as shown in the following verse:

kecit sva-dehantar-hrdayavakase pradesa-matram purusam vasantam
catur-bhujam kanja-rathanga-sankha-gada-dharam dharanaya smaranti

Others conceive of the Personality of Godhead residing within the body in the region of the heart and measuring only eight inches, with four hands carrying a lotus, a wheel of a chariot, a conch shell and a club respectively. SB 2.2.8

This jnanam is called Bhagavan by the devotees. He is called advayam because material energy is the sakti (and sakti and saktiman are one); because he is completely different from the jivas in illusion (advayam meaning unique); because the jivas are distinct amsas or parts of the whole (identity of part and whole); and because no one is in the same position as the Lord (advayam meaning having no equal). According to the devotees, though Bhagavan is pure jnana, as the yogis and jnanis agree, he has a form possessing the six qualities described by the word bhaga, which is non-material, because the form is pure consciousness. Thus it is said in the Visnu Purana:

aisvaryasya samagrasya viryasya yasasah sriyah |
jnana-vairaggyayos caiva sannam bhaga itingana ||

Bhaga of six parts is defined as: complete control, complete influence, complete excellent qualities of body, mind and words, complete beauty or wealth, complete knowledge, and complete detachment from worldly affairs. Visnu Purana 6.74

jnana-sakti-balaisvarya-virya-tejamsy asesatah |
bhagavac-chabda-vacyani vina heyair gunadibhih ||

The word Bhagvan means to be endowed with unlimited knowledge, sense power, bodily strength, power of control, influence and beauty without inferior gunas. Visnu Purana 6.5.79 Though he is situated within and without in various forms of pure consciousness with two or four hands, and though there is eternally a difference between himself and the jiva as served and servant, he is still advaya or one. That the difference between jiva and the Lord is eternal is stated in the Skanda Purana: na cyavante hi mad-bhakta mahatyam pralayad api: my devotees are not destroyed even at the time of pralaya. The word advayam negates any conception of difference, since one must consider non-difference between the Lord and his saktis, spiritual actions, and abodes.

The jnani who selects the general form of the Lord is qualified for brahman. The yogi who accepts the Lord as the soul within all beings, who possesses qualities, and who is different from the jiva, is qualified for realizing Paramatma. The devotee who accepts the Lord — who possesses an inconceivable and infinite form of knowledge and bliss, with infinite qualities and pastimes — is qualified for realizing Bhagavan. Actually he alone exists. This is shown in the following verses:

aho bhagyam aho bhagyam nanda-gopa-vrajaukasam
yan-mitram paramanandam purnam brahma sanatanam

How greatly fortunate are Nanda Maharaja, the cowherd men and all the other inhabitants of Vrajabhumi! There is no limit to their good fortune, because the Absolute Truth, the source of transcendental bliss, the eternal Supreme Brahman, has become their friend. SB 10.14.32

krsnaya vasudevaya haraye paramatmane
pranata-klesa-nasaya govindaya namo namah

Again and again we offer our obeisances unto Lord Krsna, Hari, the son of Vasudeva. That Supreme Paramatma, Govinda, vanquishes the suffering of all who surrender to Him. SB 10.73.16

madiyam mahimanam ca param brahmeti sabditam
vetsyasy anugrhitam me samprasnair vivrtam hrdi

By my mercy, you will realize my power known as the impersonal Brahman, which will be disclosed in your heart through questions and answers. SB 8.24.38

brahmano hi pratisthaham

I am the basis of brahman. BG 14.27

vistabhyaham idam krtsnam ekamsena sthito jagat

I pervade this universe by my one portion, Paramatma. BG 10.42

This is also shown by the attainment of prema for the worshippers of Bhagavan. Because the worshippers of brahman and Paramatma do not attain prema, it can be seen that Bhagavan is the root of the other forms, though Bhagavan is both brahman and Paramatma. The yogi worshipping Paramatma is superior to the jnanis who worship the brahman. But the worshipper of Bhagavan is superior to the yogis. This hierarchy is seen in the Gita:

tapasvibhyo ’dhiko yogi jnanibhyo ’pi mato ’dhikah |
karmibhyas cadhiko yogi tasmad yogi bhavarjuna ||
yoginam api sarvesam mad-gatenantar-atmana |
sraddhavan bhajate yo mam sa me yuktatamo matah ||

According to me, the yogi is better than the tapasvi, better than the jnani, and better than the karma-yogi. Therefore be a yogi, Arjuna. But I consider he who worships me with faith, with mind attached to me, to be greater than all types of yogis. BG 6.46-47

Ramanujacarya explains that the possessive case (of the yogis--yoginam) actually means the ablative case (than the yogis).