azure and domain type concept

With migrating your servers to azure, do you still have the same concept of a "domain", i.e. a list of users, computers, servers. And does the setup feel any different, i.e. as it stands all our computers can communicate with all our servers, whether they can access them depends on security - but I just wondered if your network will still look and feel the same when migrated to azure, or if its a completely different set-up. It is quite a dramatic change for us, and the end users, so I would assume the setup will be similar to how our windows domain/network is currently set up on our internally managed infrastructure..