Opinion about palantir foundry

If there's anyone who is working/has worked in palantir foundry, I would love some opinions about it.

1. What is the best approach to understand and learn the platform? I have worked mostly in SQL based platforms previously like SQL server, postgres, Snowflake.

2. How is it different from databricks? When or where should one consider using each of them?

3. Almost everything on the platform revolves around ontology. What's the best way to understand it?

Apology if it sounds like absolute beginner questions.