Databases - INTRO

RDS - Relational Database Service

MySQL, SQL Server, Oracle, etc all come under this section.

DynamoDB - Non Relational Database Service

Heavily stressed in the developer associate course. This is a No SQL database and this can be scalable very vastly.

Redshift - Amazon warehousing solution

Queried only when required like big data stored in the warehouse. Queries are not directly run the production data base as it is going to get slowed down instead we transfer a copy on the redshift and query as and when required.
This is stressed mainly in the Big Data speciality certifications.

Elasticache -

This is a way of caching the data in the cloud. Usually data that is most frequently being used.