Self-confidence vs Memory (自信 vs 記性)

zi 4 xin4 自信 confidence on myself, self-confident
ji 4 xing 4 記性 the ability to remember, memory

zi 4 and ji4 are different in the consonant.
xin4 and xing4 are also different that the latter one has a nasal tone, but you may ignore that if feel too difficult, since many mainland people cannot master it as well.