Currently Being ModeratedMar 14, 2013 5:32 PM (in response to yarimi)
Using the same Apple ID with two iOS devices does not require having the same apps on each device. I have one Apple ID and some of the apps installed on my iPhone are also installed on my iPad, but not all. The same for music, movies, tv shows, and audio and print books.
There is a setting on each iOS device to automatically download Music, Apps, and Books purchased/downloaded on another iOS device and/or with iTunes on your computer, and iTunes on your computer includes the same option.
On your iPhone, go to Settings > iTunes and App Stores. Below Automatic Downloads, turn Music, Apps, and Books off, or just turn Apps off if you want this to apply to apps only. Do the same on your iPod Touch.
iTunes on your computer includes this option at iTunes > Preferences > Store > Automatic Downloads. You may want to keep the available options on so when you download an app with either device, the app is downloaded by iTunes on your computer automatically for backup purposes.
In addition to having Automatic Downloads disabled on each iOS device, each iOS device has its own sync preferences with iTunes on your computer. You can select the apps you want installed from your iTunes library on your computer to your iPhone which can be the same or completely different for the apps you select and install on your iPod Touch. The same for any other iTunes content - music, movies, tv shows, audio and print books, and podcasts.
If you want different Apple IDs on each device, you can have apps that were downloaded with each Apple ID on one or both devices, but you must use the Apple ID that was used to purchase/download an app to install an app update on either device.