Package-by-layer groups code by technical layers (controllers/services/repos). Package-by-feature groups code by domain/feature. Feature-based structure often scales better because related code lives together and boundaries are clearer.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "package-by-layer-vs-package-by-feature-—-what’s-"
function explain() {
// Start from the core idea:
// Package-by-layer groups code by technical layers (controllers/services/repos). Package-by-
}