The stack is per‑thread memory holding call frames, local primitives and references; it’s allocated/deallocated on method entry/exit and is very fast. The heap is shared memory where all objects and arrays live; it’s managed by the garbage collector and objects usually outlive a single method call.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "java-memory-model:-stack-vs-heap?"
function explain() {
// Start from the core idea:
// Stack stores local variables and method calls (fast access). Heap stores all objects (slow
}