Pretty huge difference actually-- starting with parrotlets are from South America, parakeets are from Australia. Parakeets actually account for a huge array of species, not just the common budgies they refer to. Parrotlets are also much more aggressive than budgies, parrotlets have bigger beaks that budgies, but both birds are social. For a beginner pet, I'd probably suggest the budgie over the parrotlet simply because their pecks hurt less! (Speaking from experience!)
