Hybrid App use of local users

Hi,

I'm pretty new with mendix, and i have a very basic question (I think). Been searching the forum but cannot seem to get the right answer. So:

- I'm building an hybrid app with anonymous access, so that new users can register for the app, and get full access to the app. 

- I need to import about 6.000 users. (which currently use a different not-mendix app)

- I'll be usinig the mendix cloud.

I have three questions:

1.  What is the difference between local users and mendix AppCloud users?

2. Do I have to import these 6000 users as local users of the app?

3. When new users register, will these be registered as Local users? or as Mendix AppCloud users?