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72   96.1
May 03, 2013

What exactly is the difference between Layers and Tiers?

I have been developing apps for many years using multi-tier (or multi-layer) architectures, that is, Presentation Layer, Business Object Layer, and Data Access Layer.  The 'normal' stuff.

However, I hear more and more people talking about 3-Tier or n-Tier apps. 

My understanding is that Tier is physical (deployment) and Layer is conceptual (how code is organized), but which is which?
When is it proper to use the word Layer and when the word Tier?

Thanks for your feedback.

108   96.7
May 20, 2013
I understand it as being different as you described above. I understand it as the actual physical structure as being a layer and the the layer as being conceptual. 

Presentation Tier:        
        Client Layer
        Presentation Layer

Business Tier
        Hosting Layer
        Service Layer
        Business Layer

Data Tier
        Data Layer