Your MBP is running in "extended desktop" mode, where the two screens together make one larger area to display windows. You can drag one or more windows from the primary (internal) screen to the secondary (TV) screen. By default, the secondary screen is off to the right of the primary screen.
If you would prefer the two screens show the same image, you want to switch to "mirroring" mode. You will have to pick a single resolution for both screens, which may look poor on one or the other.
Both the relative positions of the two screens in extended desktop mode and the switch to mirroring mode can be set in System Preferences > Displays > Arrangement.