Portal method and cantilever methods are approximate analysis method.
Portal method : The portal method is an approximate analysis used for analyzing building frames subjected to lateral loading.This method is more appropriate for low rise building frame.
Cantilever method : The cantilever method of analysis is more appropriate for a tall structure, that is, for a structure that has a height greater than it's width. This method is based on the assumption that the building frame acts like a cantilever beam with the column cross sectional areas as the fibres in a beam.