"A customer who buys a SQL Server license (per-server or per-core) will be able to use it on Windows Server or Linux. This is just part of how we are enabling greater customer choice and meeting customers where they are."
I've started with the book "PostgreSQL Up & Running". It's rather lacking in detail and has a lot of typos, but I'm nevertheless enjoying it. It's written in a simple language and it provides a good landscape overview, which is exactly what you need in the beginning. Get the big picture first and then you can look for the necessary details as you go.
https://blogs.technet.microsoft.com/dataplatforminsider/2016...
"A customer who buys a SQL Server license (per-server or per-core) will be able to use it on Windows Server or Linux. This is just part of how we are enabling greater customer choice and meeting customers where they are."
Same editions, same prices.