Help me choose a LAPTOP. [Part 2]

greece or germany won't either make some larger shipping costs?

if you say it yourself if nothing else is done with that laptop and an old one can do it just the same, go for the cheaper one.

From these two? I would take the i5, even for generic use. The trailing U in i3-4010U stands for Ultra-low voltage. It is good for battery life, but bad for performance. Based on the previous machine your father will probably use this new for a long time again, so getting the stronger machine may be a good idea even if it is more expensive.
Side note: unless your father types without looking at the keys, you may want to double check that the laptop comes with some "sane" keyboard. German can be surprising already, and a Greek keyboard may be really confusing even if Latin letters are included too.

Isn't GT 840M >>>> R5 M230 by a looooooooooooooooooooooooooooong shot? (u may refer here http://www.notebookcheck.net/Computer-Games-on-Laptop-Graphic-Cards.13849.0.html for benchmark -gaming wise)
And that 1GB extra Vram will help A LOT in CAD rendering.

EDIT: And the G510 screen is only 720p (1366x768) whilst the Z50-70 is already 1080p (1920x1080)

Conclusion : Definitely Z50-70

EDIT2: the r5 is like 4 generation behind.. now laptops uses r9 graphics

tip no. 1 DON'T BUY A LAPTOP