What's the difference between a layered architecture and n-Tier architecture?

This is an amazing question!

The reason why it is amazing is that people who haven't understood anything (they haven't really grasped) are going to answer with the two definitions from the textbook, and they would be correct in what they say, AND their answer would have the funny effect in your brain of implying that you got to choose, are you going to do architecture A or B?

The fuzzyness of the human mind is a double-edged sword.

So I will answer instead the question:

How can I combine n-Tier with layered?

You can have multiple servers, one for the database, one for access control, different application services, and some holding the different business cases. Then some of them can be encapsulated each in an application layer. Imagine a business case server having on its disk the business model code. In order for this to be reachable by other servers in a meaningful way, there has to be, as code, on the same server, an application layer around it which coordinates reaching into this business model and doing something. At the same time, this application layer can have slightly overlaid adapters and ports, say for other external services doing various other tasks.

You see, right there I've combined layered, multi-tier, SOA, and hexagonal.

It might also look like those services could be microservices, but whether that is true or not depends on some “details” from the definition of a microservice: it has its own database, it's independently deployable, it reacts to and it issues events for others to capture at will.

The area of architecture gives you the tools, the definitions, the mental models, and you're supposed to take them and combine them to make YOUR architecture (a single one), just like you would combine design patterns in a program.

You also see that nowhere have I mentioned aws, any framework, any communication protocol, etc. This is exactly what I said: all these things are IMPLEMENTATION DETAILS, hidden deep under in their own layer or plugin.