Earlier quoted context omitted.
Looks like Spanner is a relational database. DDB is just a key-value pair. So, is it fair to compare against them or am i missing something?
Why wouldn't it be "fair"?
DDB -> NoSQL, No Automatic backups, No support for ad-hoc querying, eventual consistency (though you can set to get consistency with few tradeoffs) Spanner DB -> RDBMS, Automatic backups, Enriched SQL, Strong consistency.
Let me if you still think its fair to compare these 2 databases.