JIT – Compile TypeScript just in time for executing it:
- Compiled in the browser.
- Each file compiled separately.
- No need to build after changing your code and before reloading the browser page.
- Suitable for local development.
AOT – Compile TypeScript during build phase:
- Compiled by the machine itself, via the command line (Faster).
- All code compiled together, inlining HTML/CSS in the scripts.
- No need to deploy the compiler (Half of Angular size).
- More secure, original source not disclosed.
- Suitable for production builds.