What is a pre release organization?
A pre-release Organization is a limited time Org that allows user to test new features or functionality typically associated with a pilot program or an upcoming release. These are special cases and you will most likely need to signup for these Orgs or contact salesforce.com support.
Does Salesforce have the same types of organizations?
No company will have same types of Organization, based on the requirement an additional fee must be paid. In Salesforce.com we have different types of organizations in salesforce some of them are Production organization, sandbox organization, Developer organization, Partner Developer organization, Pre-Release Organization.
Can you create multiple sandboxes in Salesforce?
Sandbox organizations in salesforce can create multiple copies of your production Org for development , configuration, testing and/or training without affecting your production configuration and data . The edition that your company purchased may be entitled to sandboxes or you can purchase additional sandboxes.