- Macro: resource prioritization (army vs expansions vs upgrades), scouting to understand the opponent's macro choices, choosing the right posture in response (defensive, harassment or offensive), and resource optimization (not getting supply blocked, scaling production with income, increasing income at the maximum possible rate, removing bottlenecks, etc), scouting the enemy army composition to prepare the ideal counter army composition
- Tactics: Grand army decisions - flanks, baits, sneak attacks, hiding composition, multiprong attacks, positioning of siege units, timing attacks, knowing when to retreat (hit & run), scouting to gain advance notice of your opponent's tactics
- Micro: optimizing unit lifespan and effectiveness within an isolated skirmish for the given goal (usually to 'win' the engagement) -- pulling back weakened units to avoid aggro while it still deals damage, healing, surface area for melee units, trapping enemy units with terrain or skills, optimizing spellcaster energy usage, prioritizing targets based on multiple parameters (range, damage, cost, count, follow-ups), etc.
AI can "run" macro well, but they are poor at the macro decision-making part, which includes priority model as you mention (the responsive posture choice above and others). Up to low grandmaster tier, being significantly better at macro than your opponent while close in tactics and micro is usually enough to win consistently. It is the most impactful part of an RTS (and is where most of the 'S' lies).
But if someone was microing a battle and as a result didn't look at the minimap and see a drop arriving at their base, I can totally see concluding that this player is bad at macro as a result -- macro is referring to there being a macro cycle of tasks you have to perform all the time whether you want to or not, and non-production tasks like checking the minimap and sending in a scout seem like good examples of those tasks too.
Execution of the answers to those thoughts is in the form of tactics and micro, the other two aspects of macro. If you're following current SC2 pro meta, a "strong macro player" however has more right answers to most of those questions (Stats, Innovation) and that's their strength, versus a "strong tactical player" (TY, sOs) or a "strong micro-based player" (ByuN, herO).
That said, in high-level play, "better macro" usually refers to the other things, not just mechanically hitting stride with production, as most players in the top .01% are on the same level with those mechanics.
