Google Spanner is a Google Cloud-based database system that is ACID compliant, horizontally scalable, and global. Spanner is the database that underpins much of Google’s own data collection, and it has been designed to offer the consistency of a relational database along with the freedom of a non-relational one.
Google Cloud SQL for PostgreSQL is a fully-managed database service that makes it easy to set up, maintain, manage, and administer your relational PostgreSQL databases in the cloud.