I need to decide which version will be more intuitive:
Ver. 1 - action name in heading and open buttons:
Ver. 2 - empty heading and action name on each button:
Is it a big difference between these two options?
Questions like this are bound to generate a lot of opinion-based answers. It's very specific and it will be hard to give an academically correct answer to it.
Obviously, the two versions don't differ that much. The impact on the user experience is hard to tell. However:
In Ver. 1, the layout communicates "There is an Overview for each item. Open it here".
In Ver. 2, the layout communicates "Get an Overview of this item here".
The Ver. 2 can perhaps then be considered more straight forward, since the user can se the button and realize what it is with out going via the header to figure that out. Also, if the list of items is long, the header might be scrolled of canvas and thereby hidden making the Open-buttons make less sense; The Overview-buttons are not relying on support from another element.
The following is a very subjective though:
I really don't like repeating a button on every row in a table. I don't think it look's good and generally, the buttons are screaming for way to much attention. I don't know if it's applicable here, but I would any day of the year make the item itself clickable instead and let that provide the overview.
1) make the item name itself look clickable, like in the image below snipped from Google analytics:
2) make the whole row clickable (the on-hover symbol will tell the user and it can be enhance with a light on-hover bg-effect, if we're not talking about touch devces that is).
3) add a symbol, like the ( i ) or a small, more discrete textlink that acutally says Overview in relation to the name if the item.