Akhil Reddy Banappagari explains one difference between Oracle and Postgres:
Oracle and PostgreSQL differ significantly in their transaction models, and AUTOCOMMIT is one of those differences. We see many of our customers successfully migrate code, but still encounter variations in behavior and even runtime errors related to transaction control. Many issues happen because AUTOCOMMIT settings differ between Oracle and PostgreSQL. It is definitely necessary to understand the distinctions in AUTOCOMMIT between Oracle and PostgreSQL to ensure a successful migration.
SQL Server also has auto-commit on by default for implicit transactions like in these examples.