Google's Lambda equivalent is currently in Alpha. That said, there are bits like Cloud Logging and AppEngine that offer unique-to-Google functionality that's somewhat comparable.
(Work on Google Cloud)
http://db-engines.com/en/system/Amazon+DynamoDB%3BGoogle+Clo...
This is a bit outside of my expertise, but that page mainly points out that DynamoDB supports 3 more language-specific SDKs, while lacking ACID and what appears to be native cross-region replication (through Lambda). Until recently, Datastore was coupled with AppEngine that might explain it.
Would love to hear more thoughts from you.
(work at Google Cloud)
Is Datastore Spanner?
You can think of Hbase as a clone of Bigtable, if that helps. Bigtable is actually exposed through the Hbase API. /u/mbrukman here is the PM for Bigtable.
[0] https://cloudplatform.googleblog.com/2016/03/financial-servi...
Datastore and Bigtable have different characteristics and use cases; see https://cloud.google.com/storage-options/ for an overview.
Datastore is a document database (compare it to MongoDB), while Bigtable is a wide-column store (compare it to HBase or Cassandra).
> Is Datastore Spanner?
Datastore is built on Megastore, which builds on Bigtable. :-)
I am the PM for Google Cloud Bigtable.
Lambda and Cloud Functions are competitors, though there are some things you could do with Lambda + API Gateway that you can't quite do with Cloud Functions just yet (pretty narrow scope, though). I prefer the environment for Cloud Functions, subjectively.