Each Oracle release has many differences.
All the changes you can read here. These are Developer related. We can refer at one place.
There are architectural differences.
- Another 5 neat 12c features for Oracle developers (iadvise.eu)
Here are ideas to write Echo command in Linux shell script.
This topic shows to use the sed command in Linux to get a matching string
An example SQL query that works in MySQL shows how to use Boolean Operators in the WHERE clause.