Is there a difference between this two Pali expressions: 'janami passami' and 'nana dassana'?
'Nanadassana' can be 'knowledge & vision' of truth, per SN 56.11, as follows:
As long as my true knowledge and vision about these four noble truths was not fully purified in these three perspectives and twelve respects, I didn’t announce my supreme perfect awakening in this world with its gods, Māras, and Brahmās, this population with its ascetics and brahmins, its gods and humans.
Yāvakīvañca me, bhikkhave, imesu catūsu ariyasaccesu evaṃ tiparivaṭṭaṃ dvādasākāraṃ yathābhūtaṃ ñāṇadassanaṃ na suvisuddhaṃ ahosi, neva tāvāhaṃ, bhikkhave, sadevake loke samārake sabrahmake sassamaṇabrāhmaṇiyā pajāya sadevamanussāya ‘anuttaraṃ sammāsambodhiṃ abhisambuddho’ti paccaññāsiṃ.
'Nanadassana' can be the psychic power of 'knowing & seeing', per AN 4.41, as follows:
And what is the way of developing concentration that leads to gaining knowing & seeing?
Katamā ca, bhikkhave, samādhibhāvanā bhāvitā bahulīkatā ñāṇadassanappaṭilābhāya saṃvattati?
It’s when a monk focuses on the perception of light, concentrating on the perception of day,
Idha, bhikkhave, bhikkhu ālokasaññaṃ manasi karoti, divāsaññaṃ adhiṭṭhāti—
regardless of whether it’s night or day.
yathā divā tathā rattiṃ, yathā rattiṃ tathā divā.
And so, with an open and unenveloped heart, they develop a mind that’s full of radiance.
Iti vivaṭena cetasā apariyonaddhena sappabhāsaṃ cittaṃ bhāveti
'Janami passami' appears to be a synonym for the 1st type of nanadassana, as follows:
I know and see the scope of convictions, the scope of grounds for views, fixation on views, obsession with views, the origin of views, and the uprooting of views.
Yāvatā, āvuso, diṭṭhi yāvatā diṭṭhiṭṭhānaṃ diṭṭhiadhiṭṭhānaṃ diṭṭhipariyuṭṭhānaṃ diṭṭhisamuṭṭhānaṃ diṭṭhisamugghāto, tamahaṃ jānāmi tamahaṃ passāmi.
It's depending on the context. You should specify your Sutta for let us see the context.
In 4th Patimokkha Rule 'janami passami' means just "(unwholesome) knowing".
In some sutta "jānāmi" means "ñāṇa".
In some sutta "passami/dassana/ditthi" means "(AriyamaggaSamma)Ditthi".
In some sutta "passami/dassana/ditthi" means "seeing" only.
In some sutta "passami/dassana/ditthi" means "nama/rupa-analysis-ñāṇa".
In some sutta "passami/dassana/ditthi" are difference, but in some same.
I will collect it for you when I have time.
Knowledge is the counterpart to ignorance of the Four Noble Truths of suffering, the origin of suffering, the cessation of suffering and the path that leads to the cessation of suffering.
Vision varies according to the individual:
SN35.245:1.1: Then one mendicant went up to another mendicant and asked, “Reverend, at what point is a mendicant’s vision well purified?” “When a mendicant truly understands the origin and ending of the six sense fields, at that point their vision is well purified.”
SN35.245:2.1: Not content with that answer, that mendicant went up to a series of other mendicants and received the following answers: “When a mendicant truly understands the origin and ending of the five grasping aggregates, at that point their vision is well purified.”
SN35.245:3.1: “When a mendicant truly understands the origin and ending of the four primary elements, at that point their vision is well purified.”
SN35.245:4.1: “When a mendicant truly understands that everything that has a beginning has an end, at that point their vision is well purified.”
SN35.245:5.1: Not content with any of those answers, that mendicant went up to the Buddha and told him what had happened. Then he asked, “Sir, at what point is a mendicant’s vision well purified?”
SN35.245:6.1: “Mendicant, suppose a person had never seen a parrot tree. They’d go up to someone who had seen a parrot tree and ask them, ‘Mister, what’s a parrot tree like?’ They’d say, ‘A parrot tree is blackish, like a charred stump.’ Now, at that time a parrot tree may well have been just as that person saw it.
(the Buddha continues further with this simile to explain his vision...)