Rackspace Cloud Load Balancers | Amazon Elastic Load Balancing | |
Support | Chat/phone/ticket support available 24x7x365 | To receive 24x7x365 support for Amazon EC2, you pay the greater of $400 per month. |
Dedicated Public IP Address | A dedicated IP address allows for use as a root record for a zone. | When you create an ELB instance, you get a public DNS name; however, it’s not very user friendly and you will want to create a CNAME record in DNS to redirect to your URL. |
Access Control List (ACL) | Rackspace cloud load balancer has an ACL-based security model. | Access control list feature is not available. |
Connection Logging | Logs are sorted, aggregated, and delivered hourly to Cloud Files™, which is perfect for users who need to perform tuning, inspection, or analysis. | Connection logging feature is not available. |
Connection Throttling | Rackspace cloud load balancers have a connection throttling feature which imposes limits on the number of connections per IP address. | Connection throttling feature is not available. |
Selectable Algorithms | Customize the behavior of your cloud load balancer with selectable algorithms, including: random, round robin, weighted round robin, least connections, and weighted least connections. | ELB utilizes only a non-configurable round robin load balancing algorithm. |
Advanced HTTP Health Monitoring | Rackspace Cloud Load Balancers can use synthetic transaction monitoring to inspect an HTTP response code and body content to ensure the application or site is healthy. | While HTTP and TCP-based health monitors are available, ELB does not permit users to define an acceptable status code or body regular expression to match against. |
Shared IPs | Shared IPs facilitates easier management and better IP utilization of load balancer configuration. | ELB does not permit users to share a single IP address across multiple load balancers, but does allow for a single load balancer to support multiple port configurations. |
Internal Virtual IPs | Internal virtual IPs feature allows you to load balance internal services, without being penalized with external bandwidth charges. | All ELBs are configured as public virtual IPs. An internal virtual IP option is not available. |
SSL Termination | Does not support SSL termination at the load balancer. | Supports SSL termination at the load balancer. |
Source: http://www.rackspace.com/cloud/cloud_hosting_products/loadbalancers/compare/