The Amazon EC2 cloud is based on Citrix XenServer technology for server instances.
vCloud Express has more options related to instance provisioning details such as number of CPU cores, specific quantities of RAM to assign to the server
EC2 instances start at $.10 per hour and vCloud Express instances start at $.036 per hour.
AWS does not explicitly charge for the public IP addresses (Elastic IP addresses), but vCloud Express charges $.01 per hour for a public IP address and external Internet access for the workload
Load balancing is available in vCloud Express which is not available on EC2
AWS has a comparatively limited (about 10) operating system offering from the pre-bundled instances. vCloud Express, however, has a broader (nearly 200) offering
vCloud Express is in its beta version, lets see how it prepare itself for its long battle