Cassandra vs H2 Database: What are the differences?

## Introduction 
This comparison will highlight the key differences between Cassandra and H2 Database.

1. **Data Model**: Cassandra is a distributed database that follows a NoSQL wide-column store data model, allowing for horizontal scalability and high availability. In contrast, H2 Database is a relational database management system that follows the traditional SQL data model, emphasizing referential integrity and ACID compliance. 
2. **Consistency**: Cassandra supports eventual consistency, where data may be inconsistent for a period but eventually converges to a consistent state, whereas H2 Database enforces immediate consistency, ensuring data is always consistent at all times.
3. **Scalability**: Cassandra is designed for horizontal scalability, allowing it to easily distribute data across multiple nodes, providing high availability and fault tolerance. On the other hand, H2 Database is typically used in single-node configurations, making it less suitable for large-scale distributed deployments.
4. **Performance**: Cassandra excels in read and write-intensive workloads, especially in scenarios requiring fast writes and large-scale data storage. H2 Database, being a relational database, is well-suited for transactional workloads that require complex queries and joins, ensuring performance for small to medium-sized datasets.
5. **High Availability**: Cassandra is inherently built for high availability with its distributed architecture and replication strategies, ensuring data is always accessible even in the event of node failures. In contrast, H2 Database may face challenges in maintaining high availability due to its single-node nature, making it more prone to downtime and data loss.
6. **Deployment**: Cassandra is optimized for deployment in large-scale distributed environments, often in a cluster of nodes spread across multiple physical locations, providing fault tolerance and robustness. On the other hand, H2 Database is typically deployed in smaller, standalone instances, making it more suitable for local development or small-scale applications. 

In Summary, Cassandra and H2 Database differ in their data models, consistency models, scalability capabilities, performance characteristics, high availability strategies, and deployment scenarios.