Is there a specific way in which to identify what is cacophony and what is euphony?
"...euphony is pleasing and harmonious; cacophony is harsh and discordant."
From the Greek work origins, the difference is that cacophony is just random noise, while euphony is a harmonious blend of sounds. they are antonyms - opposites in meaning.
Euphony is achieved through the use of vowel sounds in words of generally serene imagery. Vowel sounds, which are more easily pronounced than consonants, are more euphonious; the longer vowels are the most melodious. Liquid and nasal consonants and the semivowel sounds (l, m, n, r, y, w) are also considered to be euphonious.
Cacophony, the opposite of euphony, is usually produced by combinations of words that require a staccato, explosive delivery.
More examples and descriptions here: