What is the difference between Angular CLI 14/15/16 and CLI 21?

Question

Anubhav Kumar · Answer

The Core Difference
Angular CLI 14/15/16 = Old Angular ecosystem (pre-standalone)Angular CLI 21 = Modern Angular ecosystem (standalone-first, buildless, faster compilation, much smaller bundles)
and 
Major Differences (Simple and Clear)
and 
Standalone vs. NgModule
CLI 14/15/16
Still required NgModule (AppModule, FeatureModule, etc.)Standalone components introduced (v14) but optional.CLI generated code used NgModules.
CLI 21
Fully Standalone-first.CLI generates standalone components by default.NgModule no longer needed.
Example (CLI 21):
ng generate component home
→ Creates a standalone component automatically.
and 
Build System (Legacy Webpack → New Build Tools)
CLI 14/15/16
Used Webpack-based Angular build system.Slower builds.Larger bundles.
CLI 21
Uses ESBuild + Vite under the hood.MUCH FASTER:
2–10× faster buildsInstant HMR (Hot Module Reload)Smaller production bundles
and 
Signals and Reactivity
CLI 14/15/16
Used Zone.js + RxJS for change detection.No Signals support.
CLI 21
Signals are now part of the Angular reactivity model.Optional zoneless apps (no Zone.js needed).
and 
Routing (simplified)
CLI 14/15/16
Routing required Modules → RouterModule.forRoot()
CLI 21
Routing without modules:
export const routes = [
  { path: '', component: HomeComponent }
];
and 
Server-Side Rendering (SSR) / Hydration
CLI 14/15/16
SSR existed but heavy and complex.No full hydration support.
CLI 21
SSR + CSR Hybrid (Universal + Vite)Full hydration out of the box → faster interaction.
and 
TypeScript Version
CLI 14/15/16
TS 4.7 → 4.9
CLI 21
Uses TypeScript 5.xMajor performance boost and new TS features.
and 
Developer Experience (DX) Boost
CLI 14/15/16
Basic HMR.Slower dev server.Slower unit tests.
CLI 21
Lightning-fast dev serverNear-instant reloadsESBuild test runner (super fast)Simplified project structure
and 
Optional Features
Feature
CLI 14–16
CLI 21
Standalone components
Partial
Default
Signals
No
Yes
Zone-less mode
No
Yes
Hydration
No
Yes
Vite
No
Yes
ESBuild
No
Yes
NgModules
Required
Optional (legacy)
Summary for Interview
Angular CLI 21 is a modern, standalone-first, Vite-powered CLI with faster builds, zoneless reactivity via signals, better SSR hydration, and simplified routing.
Angular CLI 14/15/16 relied on NgModules, Webpack builds, slower HMR, and no Signals support.

interview

What is the difference between Angular CLI 14/15/16 and CLI 21?

Anubhav Kumar

Can you answer this question?

1 Answers

The Core Difference

Major Differences (Simple & Clear)

Standalone vs. NgModule

CLI 14/15/16

CLI 21

Build System (Legacy Webpack → New Build Tools)

CLI 14/15/16

CLI 21

Signals & Reactivity

CLI 14/15/16

CLI 21

Routing (simplified)

CLI 14/15/16

CLI 21

Server-Side Rendering (SSR) / Hydration

CLI 14/15/16

CLI 21

TypeScript Version

CLI 14/15/16

CLI 21

Developer Experience (DX) Boost

CLI 14/15/16

CLI 21

Optional Features

Summary for Interview

Liked By

Feature	CLI 14–16	CLI 21
Standalone components	Partial	Default
Signals	No	Yes
Zone-less mode	No	Yes
Hydration	No	Yes
Vite	No	Yes
ESBuild	No	Yes
NgModules	Required	Optional (legacy)