Copy Selected Features to Clipboard - Selecting this option or Ctrl+C on your keyboard will copy anything currently selected by your digitizer tool to your clipboard.
Cut Selected Features to Clipboard - Selecting this option or Ctrl+X on your keyboard will copy anything currently selected by your digitizer tool to your clipboard and, once it is pasted it will be removed from its current location.
Paste Features from Clipboard - Selecting this option or Ctrl+V on your keyboard will paste anything currently in your clipboard to the space specified. Pasting an item with this method will remove it from the clipboard.
Paste Features from Clipboard (Keep Copy) - Selecting this option or Ctrl+Shift+V on your keyboard will paste anything currently in your clipboard to the space specified. Pasting an item with this method will not remove it from the clipboard.