We have introduced Azure Storage Services. There are other services about storage and data on Azure.
Azure Cosmos DB: A globally distributed multi-model database service.
Azure Storage: Storage for blobs, queues, files and other non-relational data.
Azure SQL Database: Azure-based Microsoft SQL Server engine for storing relational tabular data.
1: When to use Azure Cosmos DB?
When our application needs document, table or graph database, we can consider Azure cosmos DB. It also includes MongoDB.
2: When to use Azure Storage?
When we have non-relational data, such as file shares, queues messages, blobs.
3: When to use Azure SQL database?
When we have data which was using traditional data storages such as MS SQL Server and our data needs transaction support, TSQL queries.