If you have a new machine and you needed Microsoft Office installed, you bought the version you needed, and that was that. Now they are leaning consumers toward a yearly subscription and will be charging a yearly fee. Hence the Microsoft Office 365 nomenclature.
Home Premium 365 includes the line up of programs that were included in Office Professional 2010. This includes: Word, Excel, PowerPoint, OneNote, Outlook, Publisher, and Access. The one year subscription will be $100 dollars for up to five PC's.
Small Business Premium has everything Office Professionalism Plus 2010 included. This has everything listed above plus InfoPath, Access, InfoPath, Communicator, and Sharepoint. This will run you $150 a year PER user.
Both subscription versions come with some extra swag:
Home Premium gives you 60 Skype minutes a month and 20 GB of extra SkyDrive storage in addition to the free 7GB already included.
Small Business Premium customers will get get Exchange Hosting through Office 365, with a 25 GB mailbox and shared calendars. There is also 10GB of Sharepoint storage for your organization and an additional 500 MB of Sharepoint storage per user. The Lync software also gives you free video conferencing and screen sharing.
If you don't like the subscription model you can still buy the more traditional software style of Office 2013, but you'll notice a significant price hike. And like 2010, are only available to install on one machine.