Importing a CDN is essentially adding the script in a traditional manner, like this:
<script src="https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="5f292a3a1f6d7169716e6d">[email protected]</a>/dist/vue.js"></script>
The ESM build refers to an ES module that is installed in your project and utilized with a bundler (such as Webpack) by importing it like this:
import coolMethod from 'nice-package'
While both methods provide similar functionalities, the CDN approach may have limitations in terms of customization and optimization. Opt for the ESM option if possible.
This informative article discusses CJS, AMD, UMD, and ESM variations: https://dev.to/iggredible/what-the-heck-are-cjs-amd-umd-and-esm-ikm
Regarding CDNs, they are typically considered the fallback solution and not the most optimal choice. For further details, it is advisable to conduct additional research outside of Stack Overflow's guidelines.