How do I pronounce the difference of и versus й? They sound very similar and I can't really hear a difference.
Russian "и" is vowel and sounds more like double 'e', i.e. "tweet", as "й" is a consonant and sounds more like the first sound of a "young" word. Btw, you could try to listen to words at http://www.lingvo-online.ru/ to find the difference
Oй rhymes with "joy" and ои rhymes with "Joey".
Russians transliterate boy as бой. A word бои is a plural form of бой, and is pronounced distinctly differently somewhat like buyee.
So и is a vowel and sounds longer than consonant й. Your confusion stems from the feature of Russian pronunciation when Russian stick invisible й in front of many vowels, which makes it sound a little longer. For instance, when Russians say ем (I'm eating), they actually say something like yem. So in the first example бои has that invisible й in front of и.
и = "i" й = more like "y"
You can understand the difference by listening how "i" and "y" sounds in two different words: "boy" and "blink", in first case it will be "boy" = "бой" while in the second "blink" = "блинк"