What is the real meaning of 'Knowledge and Vision' in the Pali-texts? Is there a difference between this two Pali expressions: 'janami passami' and 'nana dassana'?
'Nanadassana' can be 'knowledge &amp; 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 &amp; seeing', per AN 4.41, as follows:

And what is the way of developing concentration that leads to gaining
knowing &amp; 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.
AN 10.96