/z/ and /ʒ/ are both

voiced fricatives

/p/ and /b/ are both

bilabial stops

/f/ and /θ/ are both

voiceless fricatives

/k/ and /p/ are both

voiceless stops

/ʃ/ and /tʃ/ are both

voiceless palato-alveolars

/l/ and /j/ are both

voiced approximants

Info: A lateral is a kind of approximant, though often counted as a class of its own.

/f/ and /d/ are both

consonants

Info: The voiceless fricative /f/ and the voiced stop /d/ are both "obstruents", as the air flow is blocked enough to cause audible friction.

/z/ and /v/ are both

voiced fricatives

/θ/ and /ð/ are both

dental fricatives

/b/ and /w/ are both

voiced bilabials

Info: /w/ is bilabial, but is also velar, the only Eng phoneme with a "double" articulation

/n/ and /m/ are both

voiced nasals

/s/ and /r/ are both

alveolars

Info: /r/ (the phonetic [ɹ]) can be somewhat retroflex (as in GA) or a tap ([ɾ]) or even a trill, as in Scots.

/d/ and /b/ are both

voiced stops

/w/ and /p/ are both

bilabials

Info: /w/ is both bilabial and velar

/ð/ and /θ/ are both

dental fricatives

/t/ and /d/ are both

alveolar stops

/n/ and /d/ are both

voiced alveolars