1) Presentation layer, Business Layer and data access Layer will be placed in same server
2) Logically separated parts/layers
3) Layers are the logical groupings of the software components that make up the application or service
1) Each UI( User Interface code), BL(Business Logic), DB(database) part will be placed on different servers.... (may be in different locations also)
2) Physically separated parts
3) Tiers represent the physical separation of the presentation, business, services, and data functionality of your design across separate computers and systems.
refer the following links for more details:
http://www.guidanceshare.com/wiki/Application_Architecture_Guide_-_Chapter_9_-_Layers_and_TiersRajesh081725, if this helps please login to Mark As Answer. | Alert Moderator