There are many good things in both OpenStak and Eucalyptus platforms in general. Eucalyptus cloud platform is older and well established one as compared to OpenStack that has just started operating on the real world business. There are many great features of Eucalyptus as well as OpenStack platform but the major difference between these two platforms is that of philosophy and principle.
The philosophy of OpenStack is very simple and easy to understand; it advocates through strong voice of Rackspace and other group members that cloud application should not be locked-in and should be free for everybody on the market place. This is the similar principle that led Linux to this level of success on the domain of operating systems. Similarly, OpenStack supports different APIs that help customers get full freedom of development and integration with any kind of services and applications. While on the other hand, Eucalyptus is not open source and does not advocate the philosophy and principles that are followed by its counterpart teams or groups. OpenStack platform is still in preliminary stages and it is still developing through different phases of testing and reviewing. Eucalyptus is already operating on high level of commercial application; one of the most important applications being Amazon networks or AWS services.
OpenStack has very strong backing up like Rackspace, HP, Dell and many other companies along with NASA while this condition is not true for Eucalyptus Company or platform. Thus, OpenStack is much luckier because it is supported by many great companies and giant IT players on the market place. It is a big plus for OpenStack platform. Eucalyptus is designed as Amazon EC2 compatible API; that means Eucalyptus has deep access into the market place because Amazon is a giant on cloud hosting platform and can decide about many things independently. This situation is not with OpenStack; this platform is also developed as API compatible with all kinds of companies. This does not lock-in like AWS services does for the customers. OpenStack is an open sources API supporting any kind of applications and developments; thus creating a free and flexible environment where only competition and quality will be the lock-in factors.
Scalability of Eucalyptus is not commended by big users like NASA; it is not easy to scale up and scale down. NASA also faced some issues pertaining to scalability. While on the other hand, OpenStack platform is very easily scalable and flexible. It is basically developed on the basis of modular approach of development; therefore, it is very efficient and very fast in scalability. This makes it more suitable for cloud hosting businesses because they need this feature desperately.
As far as the development and enhancements in the codes are concerned, OpenStack has many developers, supporters, reviewers, and implementers who can make this platform more efficient and effective very soon by the help of their widespread technical support. This is not available with Eucalyptus therefore any aggressive research and development is not possible for this platform to do in future.
ON the basis of above mentioned feature comparison and development environment, it can be expected that OpenStack has much brighter future as compared to Eucalyptus.