Difference between Multi-Tier and Multi-Layer?

Go through this link.This will help you to understand the difference.

In short ,

Multi-Layer-Logical layer

Multi-Tier: Physical layer

http://msdn.microsoft.com/en-us/library/ff646997.aspx
&
http://blogs.msdn.com/jmeier/archive/2008/09/06/layers-and-tiers.aspx


Hope it may helped  you!!

There are many debates on this. In my point of view;

With in one assembly we can have GUI layer, Business Logic layer, sitting in one machine. At the same time we can have three different assemblies and referenced directly in GUI layer, sitting in one machine. Also we can have all three components sitting in three systems, different assemblies and different boundaries but the same .net code. So I would say that all the above three conditions can be, may be, referred as multi layer.

When it comes to case like we have client developed in ASP.NET, business logic implemented in WCF or Web services of ASP.NET/Java or any other and Data is sitting in AS400/ORACLE/SQL Server I would say it multi tier technology where each tier can be implemented in its own technology

Layer is the logical separation of functionality into assemblies, for example, Data Layer, Presentation Layer, Business Layer etc. All the assemblies may also be deployed in the same physical machine.

Tier is all about the physical deployment.