I personally play the 4 knights but have since realised many flaws with it. It has a very small win percentage in book openings explorer and seems to be quite a drawish opening. It is quite passive and doesn't activate bishops to good, open files. The ruy and Italian offer more variation and creates a more dynamic position and have more traps and leads to a more open game for both player. Practice has shown that white has an advantage in these openings.
As for your first diagram, I've seen this before and for white it creates the idea of a closed game and they want to place a knight on D5 and pawn on D3. I think black generally can reply with symmetry and play similar ideas.
Hope this helps
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