difference “my sites” and “Network Admin” > “Sites”

Hello,

I’ve successfully setup a WP-Network but I’m a little confused with the UI and terminology.
In this screenshot I see “My sites” (the top left drop-down menu”):
http://whateverisfree.com/screenshots/my%20sites.png

Which is a little bit different from what I see at “Network Admin” > “Sites”:
http://whateverisfree.com/screenshots/Network%20Admin%20sites.png

Am I confusing something here or how can this difference be explained?

Kind regards,
Florian