One of the most fundamental dichotomy in linguistics is the phone / phoneme dichotomy:

a phone is any distinct speech sound regardless of whether the exact sound is critical to the meanings of words

a phoneme is a speech sound in a given language that, if swapped with another phoneme, could change one word to another

Phones are absolute and are not specific to any language, but phonemes can be discussed only in reference to specific languages.

Minimal pairs are pairs of words or phrases in a particular language, spoken or signed, that differ in only one phonological element.

word 1	word 2	IPA 1	IPA 2	note
pin	bin	/pɪn/	/bɪn/	initial consonant
rot	lot	/rɒt/	/lɒt/
thigh	thy	/θaɪ/	/ðaɪ/
seal	zeal	/siːl/	/ziːl/
bin	bean	/bɪn/	/biːn/	vowel
pen	pan	/pɛn/	/pæn/
cook	kook	/kʊk/	/kuːk/
hat	had	/hæt/	/hæd/	final consonant
mean	meme	/miːn/	/miːm/