I don't know where barbos gets his ideas about the Russian and Ukrainian languages. He seems to think that they are totally different.
Look at the Swadesh lists for Russian and Ukrainian. In the 1940's and 1950's, linguist Morris Swadesh made a list of words whose forms have a high degree of continuity over the documented history of language change.
Appendix:Slavic Swadesh lists - Wiktionary
Dolgopolsky list In 1964, linguist Aharon Dolgopolsky found 15 words with very highly-conserved forms (very low probability of replacement over their known history). His list, with Swadesh-list numbers:
1 (1): I/me, 2 (23): two/pair, 3 (2): you (sg, inf), 4 (11,12): who/what, 5 (78): tongue, 6 (207): name, 7 (74): eye, 8 (90): heart, 9 (77): tooth, 10 (16): no/not, 11 (79): nail (finger-nail), 12 (48): louse/nit, 13 (): tear/teardrop, 14 (150): water, 15 (109): dead (to die)
I've put them into Swadesh-list order:
1 (1): I, 2 (3): you (sg, inf), 11 (4): who, 12 (4): what, 16 (10): no/not, 23 (2): two, 48 (12): louse, 74 (7): eye, 77 (9): tooth, 78 (5): tongue, 79 (11): fingernail, 90 (8): heart, 109 (15): to die, 150 (14): water, 207 (6): name
English, Russian, Ukrainian:
I ja ja, you ty ty, who kto xto, what chto shcho, not ne ne, two dva dva, louse vosh' vosha, eye glaz/oko oko, tooth zub zub, tongue jazyk jazyk, fingernail nogot' nohit', heart serdtse sertse, to die umeret' vmyraty, water voda voda, name imja im'ja
j = y-sound, x = kh-sound like German ch
The Russian and Ukrainian words look almost identical, with a few sound changes here and there.