Ubuntu: 2 options of Restart?

Hi,

1) I have a linux workstation in the enterprise environment (Ubuntu workstation 10.04.3)

2) This workstation will get the IP address from DHCP server

3) When configuring, I have to do RESTRARTING
- The first one I use --> sudo /etc/init.d/networking restart
- The 2nd one, I use the GUI
  * From the menu line (Aplication  Places  System ...)
  * At the Extreme right, there is an icon "like Circle"; i click this I icon, and select Restart

4) It seems there is a different between the FIRST and the SECOND restart above
5) When I do the restart with the SECOND option (using the GUI)
- for some other reasons, the Default Gateway of this workstation is "gone by the wind" .....it is gone .....so other machines (in the different LAN)  can not ping to this linux workstation

6) But when I do the Restart using the firs option, the Default Gateway is given back --> so other machines from different LAN will be able to connect to this workstation

7) My questions: I need the clarification and confirmation from linux experts please

First: what is the name of the "above icon" (which location is at the extreme of the menu bar; it looks like "circle")

Second: Is there any differences of the first and the second of the mentioned RESTART above? Confirm and give a little bit of explanation please

8) Thank you

tjie