DAX Calculate function with and without FILTER

Question

Can someone explain the difference in the results of the CALCULATE function when using it with and without FILTER function? 

Given-below the scenario:

Measure21 = CALCULATE([A], 'FactTable'[Color]="Blue")

Measure12 = CALCULATE([A], FILTER('FactTable', 'FactTable'[Color]="Blue")

Answer 1

You could make [Measure12] return the same results as this: 

CALCULATE([X], FILTER(ALL('FactTable'[Color]), 'FactTable'[Color]="Blue")

Using FILTER has a significant performance impact, which can be clearly seen looking at query plans and utilization of Storage Engine vs Formula Engine.

FILTER retains and iteracts with initial filter context, while filter expression used directly in CALCULATE ignores it.