|Data Model||Key-value with JSON support. Up to 400 kb record size. Limited data type support||
|Querying||Key-value queries||Query & analyze data in multiple ways — by single keys, ranges, faceted search, graph traversals, and geospatial queries through to complex aggregations|
In both cases they perfectly suite for big data storage. Both offer cloud-based (AWS, and Mongo Atlas) and local storage solutions.
Amazon lets you buy operations per second capability rather than CPU hours or storage space.
This removes a whole lot of complexity for developers who would otherwise need to tune the database configuration, monitor performance levels, ramp up hardware resources when needed.
This provides users a fast and reliable storage space for their needs with costs that scale in direct proportion to the demand.
For now, DynamoDB looks more favourable. The fact that it’s an AWS-only engine doesn’t set any limits. Its overall stack of AWS tools that exists in their infrastructure looks promising.