IPA: /nɒnɪˈdɛntɪkəl/
KK: /nɑnɪˈdɛntɪkəl/
Not the same; different from one another.
The two paintings are nonidentical, each with its own unique style.
Nonidentical → It is formed from "non-" (meaning not) and "identical" (from Latin "identicus", meaning the same). The word "nonidentical" means not the same or different from one another.
Think of 'not' ('non-') being used to describe things that are 'the same' ('identical'). This helps you remember that 'nonidentical' refers to things that are not the same.