Explanation:
A transpiler (such as Babel) converts new syntax. A polyfill adds missing APIs. They are complementary.

ALSO KNOW (related points):
• Which website is commonly used to check which browsers support a given HTML, CSS, or JavaScript feature? → caniuse.com
• Which tool automates real browsers (Chrome, Firefox, Edge, Safari) through browser-specific drivers such as chromedriver and geckodriver? → Selenium WebDriver
• What does a web page that works in Chrome but breaks in Safari most likely indicate? → The page uses a feature or behavior that WebKit does not support, or supports differently
• Which plugin technology reached end of life in all major browsers in 2020–2021? → Adobe Flash Player
• What is WebAssembly (Wasm)? → A binary instruction format that runs at near-native speed in all major browsers
• Which shortcut zooms the page back to 100% in most browsers? → Ctrl + 0