The English language/vocabulary/verbal phrases

I think the confusion here is over whether aggressive implies a confrontational attitude or simply a competitive or driving approach.  The answer is it can mean both depending on the context.  And I think what Hackettfan means when he says attack in sport is a metaphor is that you do not literally attack, as in physically assault, the opponent.  You tactically force yourself on him within the rules of that sport.  So in boxing, attacking does come very close or in fact amounts to an actual physical assault whereas in tennis it would simply mean trying to take the net away and finish the point and in cricket, using the front foot and driving rather than blocking the ball.  In chess, it would mean forcing a move from the opponent that would involve loss of coins for either side.  In all of the last three contexts, there is no actual assault, it's only attacking within the limited context of the game. But since attacking, unlike aggressive, is not used in a behavioural context at all (where aggressive is contrasted in a negative light with assertive), I prefer the former in a sporting context.

I see what you are saying but I don't see that 'attacking' (and thus 'aggressive') is figurative (or 'metaphoric') in these contexts just because it isn't a physical attack. When you fall in love the 'fall' is figurative, but when you attack an opponent in a sporting game the 'attack' is not figurative, the meaning does not magically switch from literal to figurative when the action does not involve physical contact, it remains the same. Attacks in war-games and military exercises do not become metaphorical just because non-live ammunition is used. Historically all 'sports' were a non-lethal form of military training and every game has an opponent even when competing against yourself. All the terms and synonyms we have used [in these posts] in those non-physical contexts to describe aggressiveness are related to literal attack: confrontation, offence, force, opposition, [to which we can add assault, assail, pounce, strike, storm, grapple, etc.] ... As Todd said, 'getting in someone's face' is related to that and so is 'advance' and 'push forward', their meaning in these contexts comes from the act of attacking in a literal sense.

In any case, seeing the differentiation of the two meanings, I do not see anything inherently wrong with using two different words. Perhaps strictly speaking, "aggression" would be more correct in English no matter what are we actually meaning, but if the use of "aggressiveness" in certain situations can help in making a distinction, clarifying that we do not mean any factual aggression or attack, but more the Spanish interpretation of "agresividad" (being bold, challenging, ready to take risks etc) I don't see it so bad.

A few anecdotes...

'tis a good one and another that shows how British English evolves faster than American English. 

It's also an example of a noun used as a verb that the Brits tend to avoid. Orient was originally a noun meaning "East", as a verb it meant to align with the points of a compass, namely 'East', from this we get the noun Orientation. Orientate is a back-formation from this new noun, and since we like to avoid nouns and verbs we made a new verb Orientate to replace Orient, allowing us to keep the original "East" meaning.

It means we can say Orient Express with out thinking it means Alignment Express