Questions about userinstances

[Cal Who]

I just installed sql express and have some questions.

I use aspnet and sql to create a database.

I can do it with userinstance true or false.

they seem like two different spaces.

That is I seem to be able to have databases in each.

I installed with the default instance.

Do I now actually have four instances:

.\SQLExpress userinstance true
.\ userinstance true
.\SQLExpress userinstance false
.\ userinstance false

I doubt the above is true but I'm confused about what I see and don't know
what to ask.

When connecting I can connect to DAD or
DAD\SQLEXPRESS

I was suprised to see DAD\SQLEXPRESS expecting only the default instance.

How does userinstance show up in sql server management

Thanks in advance