Microsoft provide a nice comparison list of all the available 365 plans for business.
However when planning to move to Office 365, you may not have considered the implications of initially choosing a particular plan. You may also have a number of different licences for different users in the organisation (you don’t have to stick to one plan). For example some users may need to download office on their machine (accountants using the full desktop version of Excel) and some may just need a mailbox. I briefly go over the different plans in the video below.
Remember that business licences are for users who don’t need centralised deployment and control. Small businesses may opt for the business licences while larger ones may need some compliance and centralised administration.
Just a quick note on upgrading licences for older tenancies using the Office 365 small business plan. I recently worked with a client using the old Small Business licences, they wanted to upgrade to enterprise but due to it being on the old 365 platform, it wasn’t possible to upgrade from within the admin centre. The only option to upgrade was to create a new tenancy, manually migrate PST files (exchange) and re-sync document libraries (SharePoint) up to the new tenancy using OneDrive for business sync tool. Very annoying and a lot of work! However all users on the new platform with Business licences can upgrade their licences in-place by going to the subscriptions page. I have also been informed by Microsoft that these older plans cannot be renewed after October 2015 and Microsoft will offer some migration options before the licences run out.