(1). Drag+Drop the file(s) from folder1 to folder2 will move file(s) as well-that means the files will be deleted from folder1 and show up in folder2. This only works if folder1 and folder2 are in the same volume. (default Macintosh HD)
(2) If you want move files from folder1 that is on volumeA to folder2 which is on VolumeB, hold down the Command (⌘) and drag the files from folder1 to folder2. If you don’t press down the ⌘ key while dragging. the files will be copied from folder1 to folder2.
Image Credit: Mads Bødker