Snowflake has their own sql engine and is more of a serverless option. Databricks started off with spark but now also has a sql engine(optional serverless) as well, they are using spark in the article.

The delta format is Databricks lakehouse file format, snowflake uses iceberg I believe.

Both Snowflake and Databricks also provide a ton of other features like ML, Orchestration and governance. Motherduck would be the direct competitor here.

Saying that there are now extensions to query snowflake or databricks data from duckdb for simple ad hoc querying.

Duckdb is fantastic and has saved me so many times strongly recommended.