Reputation is what you seem; character is what you are.
Literal
Reputation [topic-は] appearance [copula-であり] character [topic-は] person [possessive-の] essence [copula-である].
A philosophical aphorism. であり is the conjunctive form of the formal copula, linking two parallel statements. 外見 ('appearance') contrasts with 本質 ('essence'). The parallel structure is characteristic of maxims.