Q. What is the difference between Verna 1.4 CRDI engine and i20 1.4 CRDI engine and what about the mileage between these two

There's no differences, it's the same engine with the same tunings. Verna would be more comfortable and fun to drive in both highways and city traffic. But can't expect that from i20. The answer for your question would be without any doubt VERNA IS BETTER THAN I20. HOPE IT HELPS. :)

Engines are same, body type difference is there, sedan is always better in looks handling and space

I have verna flusic crdi 2013 1.4 ex i drove and feel extra mile power in driving i don't understand when i20 come with same 1.4 then why not the same power