In a B+ tree, all records (or pointers to records) are stored in the leaves, and internal nodes store only keys for routing. Leaves are usually linked, so range scans are very fast. This fits disk access well: high fan-out keeps the tree shallow, and linked leaves make ordered reads efficient.
Advanced answer
Deep dive
Expanding on the short answer — what usually matters in practice:
Complexity: compare typical operations (average vs worst-case).
Invariants: what must always hold for correctness.
When the choice is wrong: production symptoms (latency, GC, cache misses).
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 "b-tree-vs-b+-tree:-what-is-the-practical-differe"
function explain() {
// Start from the core idea:
// In a B+ tree, all records (or pointers to records) are stored in the leaves, and internal
}
Common pitfalls
Too generic: no concrete trade-offs or examples.
Mixing average-case and worst-case (e.g., complexity).