Transpile ↔ (process) to translate Source Code into some other Source Code

Babel

Dev tool to Transpile JSX & Polyfill JS

References

1. JSX ↔ Syntactic Sugar to mix HTML inside JS, later Transpile to React.createElement()

2. JS Bundle ↔ single combined JS Code output for Client to run, often Transpile to ES6 for compat

3. Build Tool ↔ Dev tool to Transpile & Bundle project

4. Preprocessor ↔ Dev tool to Transpile Code Superset to other (base compatible) Code

5. ESBuild ↔ CLI Dev tool to Transpile & Bundle JS, fast efficient Compiler built in Go

6. Downlevel ↔ (TS term) to Transpile to older JS version

7. Babel ↔ Dev tool to Transpile JSX & Polyfill JS