Aristotle's immanent realism means his epistemology is based on the study of things that exist or happen in the world, and rises to knowledge of the universal, whereas for Plato epistemology begins with knowledge of universal Forms (or ideas) and descends to knowledge of particular imitations of these.
ˈæɹɪstˌɑːɾəlz ɪmˈeɪnənt ɹˈiːəlɪzəm mˈiːnz hɪz ᵻpˌɪstɪmˈɑːlədʒi ɪz bˈeɪst ɔnðə stˈʌdi ʌv θˈɪŋz ðæt ɛɡzˈɪst ɔːɹ hˈæpən ɪnðə wˈɜːld, ænd ɹˈaɪzᵻz tə nˈɑːlɪdʒ ʌvðə jˌuːnɪvˈɜːsəl, wˈɛɹæz fɔːɹ plˈɑːɾoʊ ᵻpˌɪstɪmˈɑːlədʒi bɪɡˈɪnz wɪð nˈɑːlɪdʒ ʌv jˌuːnɪvˈɜːsəl fˈɔːɹmz ɔːɹ aɪdˈiəz ænd dᵻsˈɛndz tə nˈɑːlɪdʒ ʌv pɚtˈɪkjʊlɚɹ ˌɪmɪtˈeɪʃənz ʌv ðˈiːz.