Phonetically, they differ only in a feature called voicing; /p/ is unvoiced (the vocal cords don’t vibrate), while /b/ is voiced (the vocal cords vibrate).
Consider the English sounds /p/ and /b/. Phonetically, they differ only in a feature called voicing; /p/ is unvoiced (the vocal cords don’t vibrate), while /b/ is voiced (the vocal cords vibrate). However, phonologically, they can create different meanings in words: 'pat' versus 'bat'. Phonology would explore not only these differences but also how these sounds interact with others in the language system, like how the plural /s/ sound changes depending on the preceding sound: it’s pronounced as /s/ after /p/ in 'caps' but as /z/ after /b/ in 'cabs'. This illustrates phonology’s interest in the function and organization of sounds within a language.