In most software, such as Word, the only difference between 'copying' and 'moving' is that when you move something the original is deleted. When copying the original remains. In Excel there is a significant difference.

The mechanics of copying are similar to those for moving, except that if you use the drag and drop method you must hold the ‘Ctrl’ key down throughout the copy operation

The difference is that when you 'move' the addresses in the formula change so that they are at the same relative position. The example below illustrates this:

METHOD 1
Run the flash animation to compare it to the 'Move'. It is identical until the very end when the formula in the cell 'D9' is '=C7 + D7' rather than '=C3 + D3'. The original formula, in Cell D5, has not changed. If this is not clear now, then the next couple of pages should help. Click the Button to Play >

 

METHOD 2

Alternatively you can use the 'right click option'': Select the range you want to copy. Right click to get the submenu and select Copy Select the destination cell (left click) Right click to get the submenu again. You now have a number of Paste Options that weren't available with the 'Cut': For a simple copy select the icon on the left (the clipboard). I'll discuss some of the others shortly.   Roll your mouse over the image to see the 'Paste Options".