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 a vowel and sounds more like the double 'e' in "tweet", while "й" is a consonant and sounds more like the first sound of "young". Btw, you could try to listen to words at http://www.lingvo-online.ru/ to hear the difference.
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.
The Russian "и" sounds like the vowel [i] in the International Alphabetical Alphabet (IPA) and like the letters 'ee' in the English words "bee", "see" and "tweet".
The Russian й" sounds like the semivowel/consonant [j] in the IPA and like the letter 'y' in the English words "young", "year" and "you", and the letter 'u' in the English words "use" and "unit".
The difference between both is that the middle part of the tongue is raised to the hard palate only in [j]. I suggest watching this video: https://youtu.be/XhqGU1WxOfc .