What is the need of portal application (PA) instead of web application (WA)?

  We cannot see more than one WA in WAs, whereas in PA, we can see different WAs.

 We can declare the pages using layout in PA & not possible in WA. 

  We can access DB with all different concepts in PA and not possible in WA.

  Coding is very less in PA compare to WA.

  Authentication problems in WA, very easy in PA

  PA is slower than WA