There are several ways to create a new Office 365 domain and at the moment there are several different types of domains available. There is the standard Office 365 offer, the Office 365 Enterprise Preview (built on SharePoint 2013) and finally the hard core Office 365 Developer Site.

Office 365

To create a domain for a school, company or institution, create an ordinary Office 365 domain. There is a 30 days trial and you will have time to test the domain thoroughly. If you want to use the Office 365 for Education offer you sign up for the trial, assign your institution address to it and have Microsoft verify eligibility.

http://www.microsoft.com/en-us/office365/default.aspx

Office 365 Enterprise Preview

Office 365 Enterprise Preview is the latest and coming version of Office 365, built on SharePoint 2013. You can sign up for a free trail which has a longer expiration time than the regular Office 365 trial site. With the preview you get 25 account to play around with Office, SharePoint, Lync and Exchange.

http://www.microsoft.com/office/preview/en/office-365-enterprise

Office 365 Developer Site

Office 365 Developer Site is the type of domain you need to get. With an Office 365 Developer Site you only get one account, but that’s all you need to start creating apps for Office 365.

http://msdn.microsoft.com/en-us/library/fp179924(v=office.15).aspx