You have two different terminals installed, the default Ubuntu terminal and a terminal called Terminator.
You use two different launching methods, one with a shortcut key (Ctrl+Alt+t, and one using a desktop launcher in the toolbar.
It is up to you to configure your system such that an action you take does what you want. Thus, depending on the terminal emulator you want to use, change the launcher icon or change the command assigned to Ctrl+Alt+t. The details on how this is done dependent on the desktop environment you use. From the picture you posted< I guess that might be Unity.
It seems you have Terminator (2nd pic) installed in your system (a different terminal emulator than the system one)
If you don't want to use it, a quick solution would be to uninstall it
It'll restore your ctrl+alt+t shortcut back to the default one.
Update: If you don't want to uninstall, follow these steps to restore your default terminal.
you'll get this result.
This is the list of terminal emulators in your system. See for me default terminal is Terminator ( number 0 ) and it has a * next to it.
you have to choose which terminal you want to select as default.
Type the desired list number, Press enter, now it should restore your default terminal.
You have two different terminals installed, the default Ubuntu terminal and a terminal called Terminator.
You use two different launching methods, one with a shortcut key (Ctrl+Alt+t, and one using a desktop launcher in the toolbar.
It is up to you to configure your system such that an action you take does what you want. Thus, depending on the terminal emulator you want to use, change the launcher icon or change the command assigned to Ctrl+Alt+t. The details on how this is done dependent on the desktop environment you use. From the picture you posted< I guess that might be Unity.