1. Load Balancing Algorithm: AWS Elastic Load Balancing (ELB) offers a variety of load balancing algorithms such as round robin, least connections, and IP hash, allowing users to choose based on their specific requirements. In contrast, Semaphore uses a round-robin load balancing algorithm by default, providing a simpler approach without advanced customization options.

2. Integration with AWS Services: ELB seamlessly integrates with other AWS services such as Auto Scaling, making it easier to scale resources based on demand. On the other hand, Semaphore does not have direct integration with AWS services, requiring manual setup for scaling functionalities beyond load balancing.

3. Health Checks: ELB performs regular health checks on instances to ensure they are healthy and can handle incoming traffic efficiently. Semaphore also conducts health checks; however, the configuration and monitoring of health checks are more customizable and detailed in ELB compared to Semaphore.

4. SSL Termination: ELB supports SSL termination, allowing encrypted traffic to be decrypted at the load balancer before being sent to backend instances. In contrast, Semaphore offers limited SSL termination capabilities, making it less suitable for managing secure HTTPS connections.

5. Cost Structure: The pricing structure of ELB is based on the usage and the type of load balancer chosen (Application Load Balancer, Network Load Balancer, or Classic Load Balancer). On the contrary, Semaphore follows a simpler pricing model with a flat fee regardless of the features and options used, making it more predictable for budgeting purposes.

6. Customization Options: ELB provides extensive customization options for advanced users, including access to low-level settings and configurations. In comparison, Semaphore offers a more straightforward approach with fewer customization options, catering to users who prefer simplicity over complexity.

In Summary, AWS Elastic Load Balancing (ELB) and Semaphore differ in load balancing algorithms, integration with AWS services, health check capabilities, SSL termination support, cost structure, and customization options.