These images are ideal for customers looking for short-term, project-based SharePoint deployments for a test "sandbox" and proof of concept efforts. They should also save you time deploying and help you avoid burning up resources by spinning up a VM on your laptop.
Both images include all of the components necessary for a fully functioning SharePoint deployment, including a web server and database, all on a single server. While they lack some enterprise features, they meet general SharePoint needs.
The SharePoint image you choose depends on what you hope to accomplish. Both instances include SharePoint 2010 Foundation. The key difference between the images is that one is a stand-alone install with Microsoft SQL Server Express, while the other is a complete farm install with Microsoft SQL Server Standard, Visual Studio and Active Directory.
What does that mean?
The instance with SQL Server Express will cost you less because Microsoft provides this version at no cost and without any licensing fees. While it is free of licensing fees, Microsoft SQL Server Express has a maximum database size limitation of 10GB per database. You should only select this instance if you know you will have a small amount of files with a limited number of users. Otherwise, you could walk in one day and discover that SharePoint is down because you have run out of space. To avoid this, you can select the instance with SQL Server Standard, which will remove the 10GB database limitation. While you do have to pay Microsoft licensing fees for SQL Server Standard, your database can take full advantage of all the space available on your Cloud Server.
Another thing to note is that the instance with SQL Server Express is set up as a stand-alone deployment. As a result, it cannot later be added to a SharePoint farm.
If you anticipate the need to scale up to a larger environment in the future or add an additional Web Front End (WFE), you may want to consider the Rackspace SharePoint image that includes the full version of Microsoft SQL Server Standard. This instance is a complete install of SharePoint Foundation 2010 in a farm, but deployed on a single Cloud Server.
The instance with SQL Server Express also does not come with Active Directory installed, while the image with MS SQL Standard includes Active Directory.
You might wonder; how does that work?
The image with SQL Server Express uses local accounts where Active Directory service accounts would typically be used. Users authenticate against local accounts on the server itself; user permissions and restrictions are unique for that server. This is fine if you are only using one server and never intend to add it to a SharePoint farm. And as we described earlier, this install was done as a stand-alone deployment, so you won't be able to do that anyway.
The instance with SQL Server Standard comes with Active Directory, which you need to utilize when you connect to a SharePoint Server farm. This instance is a single server deployment, but it has the capability to be added to a larger farm and thus needs Active Directory. Because this deployment has Active Directory and a full version of SQL Server, it could be used as a production SharePoint site in a pinch, despite it not necessarily following some of the recommended best practices for a production SharePoint site, specifically because it's deployed on a single server.
And if you need additional support for these SharePoint images, Rackspace Professional Services for SharePoint has a suite of service offerings you can leverage, feel free to contact them with any questions you have at email@example.com.