The difference between relational and reactive aggression is that relational aggression is whereas reactive aggression is

Social, physical behavior

Explanation:

The relational aggression is the aggression which caused or give to person by doing harm to his or her relationship or social image.

Reactive aggression is the aggression which is caused by threatening someone, or caused by provocation, or caused due to frustration.

Therefore, the basic  differentiation in  between both the aggression is that relational aggression is caused by by damaging social status whereas reactive aggression is caused through physical behavior.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .