The answers here are not completely accurate, outdated, and do not give a full explanation.
When should I use each one?
tl;dr In general use --base-href, because --deploy-url
- is deprecated as of Angular v13
- will decrease build speed (although, probably not too significant)
- does not have the benefits of
base href in "locating relative template (HTML) assets, and relative fetch/XMLHttpRequests."
If you need the URL to be different than where the assets are placed, the official documentation recommends setting APP_BASE_HREF manually (and differently, e.g. set --base-href to /public/ and APP_BASE_HREF to /users/ if you will serve the Angular files at https://example.com/public/ but you want the web app's URL to be https://example.com/users/)
What's the difference between --base-href and --deploy-url parameters of angular-cli tool?
Above I've already listed 3 differences.
As you have already stated in your question, --base-href sets the <base href> in the index.html (for details see the Mozilla docs and for implications see the community wiki), while --deploy-url prefixes the relative links inside the index.html file.
For example, the following index.html snippet:
<link rel="stylesheet" href="styles.HASH.css">
...
<script src="main.HASH.js" type="module"></script>
With --deploy-url /public/, will be outputted as:
<link rel="stylesheet" href="/public/styles.HASH.css">
...
<script src="/public/main.HASH.js" type="module"></script>
--deploy-url seems to literally just prefix the links, so if you instead did --deploy-url public, the output would be pretty much unusable:
<link rel="stylesheet" href="publicstyles.HASH.css">
...
<script src="publicmain.HASH.js" type="module"></script>
Lastly, if you have a template (HTML) that uses a relative link to an asset, e.g. a header.component.html that contains <img src="assets/logo.jpg">, but you use --deploy-url /public/, the link will not be prefixed and will give you a broken image. This would instead work if <base href="/public/"> is set using --base-href /public/.