Have you ever wondered how MySQL and PostgreSQL are different? Take a look at the mapping that I have made for myself: https://www.mssqltips.com/sqlservertip/5745/compare-sql-server-mysql-and-postgresql-features/
I would be happy to see comments posted for this blog and add more things to the mapping.
Yours
Maria 
P.S. The ranking screenshot was taken from db-engines site: https://db-engines.com/en/ranking/relational+dbms