A Channel belongs to an individual (always a moderator) and is customizable the owner. The channel will have the word "Channel" in the URL. The channel houses all of the videos uploaded by the channel owner and can also be uploaded to directly if the option to do so is turned on.
A School Community page houses all of the videos uploaded by all of the users registered under that specific school/ organization. The school community page will have the term "Organization" in the URL. The school community page is not customizable at all at the moment. It is simply an area to see all of the videos uploaded by all users at a school/ organization.