It's the classic micromanagment vs macromanagment that started in War2. It's not really that seas is more tactical, and Matty's play is abstract, that's simply how they choose to play in the finals. I'm sure they could play both styles.
The micromanagment viewpoint is simple unit countering. You spend most your time picking and then fighting with your units. You always fight the battles and never leave the scene during one. The main goal is to win the fights economically. That is, kill more resources worth of units than you lose. Units for this style include compos and stable units.
The macromanagement viewpoint is to overwhelm the enemy. You're not actually fighting the battles. After moving the troops in place, you are creating more troops and tending to the economy. (which in turn gives you more troops). You will lose more units then your opponent, but you will field more as well. The key military unit in this style is the chariot archer. Fast, ranged, and requires the two most abundant resources.
Both styles can win, it clearly depends on who plays better. If you kill 10 units and lose 5, but are being outproduced 30 villagers to 10, you're gonna lose. However, keep the average of double military efficiency and jack your economy to 2/3 the enemy and you'll win the resource game.