What's the difference between creating a category for just a specific product/service vs. for the entire company? (Micro vs Macro category creation)

I don’t see a difference actually, at least for technology companies. At the end of the day, customers don’t want your product, they want outcomes that your product (and company) help them derive.

Few examples:
• Uber/Lyft sell the ability to get from point A to point B without a car. The app is just a vehicle (pun intended).
• AirBnB sells the ability to belong / feel at home anywhere in the world.
• Etc.

Start by deeply understanding your persona and work backwards from there. Understand the jobs they’re looking to tackle and how your product and company both have a role to play in concert with each other.

• A micro category is relevant for specific product/service as it provides a niche use case that the offering supports. 
• A macro category for a company is the high-level category that aligns with customer needs and expectations in the industry.

Both micro and macro categories co-exist and it’s crucial to help teams understand the dimensions needed for both categories. Macro category can have breadth while a micro category needs more depth. 

Eg: If the macro category is Integration Platform as a Service (iPaaS); a micro category could be Application and Data Integration, API Management etc.