Difference between BSP application and BSP Alias

Hello

while creating a BSP iview in Step 3 its asking me a Definition Type Of BSP

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Select whether you want to create a BSP application or BSP alias iView

BSP Definition Type: *

Application

Alias

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what is the diff between BSP application or BSP alias iView and why they are used

can anyone help me out....

useful answers would be acknowledged with rewards

Regards

JM