Akaito is basically Vocaloid Kaito, but in a red color scheme instead of his usual blue. 赤 is the kanji for red, which is read as あか (aka). So a Red Kaito = AKAito.
Said to like peppers (hot, spicy) while Kaito likes ice cream (cold, sweet). Both Akaito and Kaito can also be classified as Red Oni and Blue Oni respectively.