Actually, you can install Social Office CE on Liferay EE. See the Social Office Marketplace page here: https://www.liferay.com/marketplace/-/mp/application/15190404 and check the Current Requirements:
Liferay Portal 6.2 CE GA1+
Liferay Portal 6.2 EE GA1+
In general, if a Liferay app has "CE" in the title, it's for CE only. And if it has "EE" in the title, it's for EE only. I think Social Office is an exception since it's possible to purchase a Liferay EE subscription but not a Social Office EE subscription. In this case, a Liferay EE subscriber can still use Social Office CE.
