Question about selecting cells in Excel?

Question

excel

Hello!
Tell me, what is the difference when we select several cells with the left mouse button, simply dragging over the cell area, and when we "cling" the selected green rectangle to the lower right corner and all the values ​​in the selected cells become the same?
Here is an example -

Example

Thanks

Answer 1

Straight aerobatics trolling. So I can't join.
The first case is cell selection.
The second case is copying from the selected cells to those included in the expanded selection.
And if the second case is done with the SHIFT key pressed, then it will happen sooooooo-o-o-o-oo....

Answer 2

In the first case, you simply select cells for further actions on them.
In the second case, there is a change in values ​​and formulas according to certain rules.