What do Attack and Defence Actually Do?

This is a question I've wondered for a while. When considering how good a player is at "Attacking", you think of whether he could break a line (either by running through or in between people), whether he could create a linebreak with a fantastic pass or whether he could finish off moves with a burst of pace. But don't we already have Strength, Agility, Handling and Speed for this? Similarly, for "Defending", don't we have Strength, Technique and Speed which seem to cover everything you'd need to actually make a tackle?

Do Attack/Defence just relate to something along the lines of 'vision' and 'positoning' or am I missing something and are they much more important?

I like to think that stronger players gain metres/linebreaks through a combo of attack + strength(+weight) + speed (to a lesser extent normally due to it being lower) and more agile players gain metres/linebreaks through a combo of attack + agility + speed, and that these figures are compared to the player they are facing in the line/opposite number(don't know how it's done), but instead the defender is using the defence stat.

And I think attack affects the number of linebreaks triggered by a player, the completion rate(where speed/agil comes in as well) and handling(for both players involved) comes in when passing is involved in the linebreak

Attack, as far as I'm aware, will also include support play and movement.

yeah i would think it includes support play and positioning during multiple phases and linebreaks.

i would say defence includes the ability to work as a team to a high standard too rather than just an individual, it also makes them better at defending 2 on 1s and so on aswell as basic positioning and that