What should you pay attention to when working with PostgreSQL if you are an oracle writer?

Question

PostgreSQL

Dbashniks from both fronts are invited to the thread.

Feeling some trends, I want to study postgres (so that if anything, it would be easier to change the fiefdom).
In this connection, the question is - what should you pay attention to when you study postgres, while knowing Oracle well (very well)? What are the root features that will have to be smoked for a long time and with diligence?

Answers "yes, that's all, these are different subds" are not accepted, speak to the point.
If anyone knows good postgres guides for dbashniks, please share.

Answer 1

www.sql.ru/forum/1160776/arhitektura-postgresql

Answer 2

I won’t say anything about the difference between PostgreSQL and Oracle, but I recommend reading: postgresql.leopard.in.ua