Scaling in object and edit mode My question is: why do Object mode scaling and Edit mode scaling seem to be incompatible?
I'm quite new to blender, so I may not know sth important about these modes.
The actual case is: 
I create a cube, which is 2×2×2 metres in metric units by default 
(it's also shown under 'dimensions')



Then, with the cube selected, I switch to Edit mode, and enable 'Edge info: Length' under 'Mesh display'



And it shows the cube's measurements, which are 2m on each edge. 
Now I use the scale tool in Edit mode, making the edges 2.244m



That's good so far. Changing back to Object mode, the changes can be seen under 'dimension'



However, when I use the scale tool in Object mode, the scale and dimensions also change, but changing back to Edit mode, the measurements shown remain the same





So the question is, why does the scale tool work differently and have different effects in Ojbect mode and Edit mode?
Also, how can I enter the desired size of my cube manually to get an accurate result, without using the scale tool in Edit mode, and without changing the scale ratio in object mode?
The object-mode scale is a property of the object; it doesn't actually do anything to the mesh, but rather affects how the mesh is going to fit in the scene.

Scaling in edit mode actually moves the mesh around; it's equivalent to selecting and carefully moving vertices around to make the mesh bigger or smaller.

There are many situation where you don't want to touch the object scale (e.g. physics simulations tend to get mucked up).

If you have changed the object scale, but really meant to scale the mesh, you can "apply the scale" (i.e. apply the object's scale to the mesh, and set the object scale to 1) by ctrla and select "scale" in the popup menu.