I am trying to find event that fires right after updating the shipping address / billing address of an order via the magento admin.
like http://stackoverflow.com/questions/31468618/need-a-magento-event-that-will-fire-after-changing-the-s... this i want to do in Magento 2.
One event which you can use is:
Inside the observer, you can access the address by calling $observer->getData('address'). You will probably have to check whether the address is newly created or not (i.e. by $address->isObjectNew()). If you define the event in the etc/adminhtml/events.xml, you won't catch frontend changes.