What's the difference between 耐心 and 耐烦

耐心：n./adj. patience；for example: 他是一个耐心的人(He is a patient man.).
他很有耐心地给小朋友讲解题目.(He was very patient in explaining the topics to the kids)
耐烦：adj. be patient. Restraining one's irritability in the face of upsetting situations and tolerating unpleasant things or behaviors. Usually used in negative sentences or rhetorical questions。（不耐烦impatient）
Often paired with words that tend to evoke negative feelings in people。（对噪音很不耐烦：Very impatient with noise）
for example: 车还没来，他已经很不耐烦了。The bus hasn't come yet. He's already impatient.

when we choose '耐烦' in daily life ,we always use it as a group with '不'（as well as‘不耐烦’） to express the meaning of 'impatient', instead of using the ’耐烦‘ only.
In simple terms, if we want to express the meaning of 'impatient', we choose to use '耐烦' with '不', which is namely '不耐烦'. Else if we want to express the meaning of 'patient', we use the '耐心'.