Internal Storage size is less than I have the Micromax Canvas A1 AQ4501 device. On various pages, as as this one, it's internal memory is listed as 4GB.

But, when I go to Settings -> Storage, under Internal Storage it says total space is 2.27 GB. The app Hardware Info also lists a similar amount: 2322 MB.

Where is the rest of my storage? :O

(Is it that the rest of the storage is taken up by OS etc, duh?)
The shown free space is without the size of the whole Android system. Your internal storage has a total amount of 4GB (Sometimes there is less because the manufacturer defines 1GB as 1 billion bytes). And the Android System and preinstalled apps are also using space.