However, the more recent Google storage offerings based on Cloud Spanner do seem to offer this. I don't see how Amazon can make this statement - that doesn't stop it being an excellent enhancement to DynamoDB though.
DynamoDB is limited to 10 items, whereas the Cloud Datastore limits are 25 different 'tables' -> The new version via Cloud Firestore doesn't even have that restriction. AWS is several years behind and several NoSQL systems behind in this area. Still, a cool addition.
The “and tables” clause is the differentiator, I think. DynamoDB tables are roughly equivalent to Datastore namespaces; I don’t believe Google Cloud Datastore supports cross-namespace transactions.
I don't think it's fair to compare them.
However, the more recent Google storage offerings based on Cloud Spanner do seem to offer this. I don't see how Amazon can make this statement - that doesn't stop it being an excellent enhancement to DynamoDB though.