Enums define a fixed set of instances of one type. Sealed classes define a restricted class hierarchy where each subclass can carry different state. Both enable exhaustive when, but sealed classes are more flexible for modeling complex variants.
Advanced answer
Deep dive
Expanding on the short answer — what usually matters in practice:
Context (tags): sealed-class, enum, when, kotlin
JVM: memory (heap/stack), GC, and what drives latency.
Contracts: equals/hashCode/toString, mutability and consequences.
Explain the "why", not just the "what" (intuition + consequences).
Trade-offs: what you gain/lose (time, memory, complexity, risk).
Edge cases: empty inputs, large inputs, invalid inputs, concurrency.
Examples
A tiny example (an explanation template):
// Example: discuss trade-offs for "sealed-classes-vs-enums-in-kotlin?"
function explain() {
// Start from the core idea:
// Enums define a fixed set of constants. Sealed classes define a closed type hierarchy where
}
Common pitfalls
Too generic: no concrete trade-offs or examples.
Mixing average-case and worst-case (e.g., complexity).