NIFT  is for fashion designing and other related fields...but..NATA is only for architecture...

For NIFT

1. You study current affairs, english, general maths and drawing abilities which includes designing poster or logo. Something which measures your designing aspects
2. There are 2 papers, one drawing paper another general ability test.

For NATA

1. You study architectural awareness, general maths (hardly 2-3 questions are expected), synonyms and antonyms and visualisation. The drawing paper includes view, ant's eye view etc. Something which measures your skills in perspective.
2. There are 2 papers, one drawing paper and another 50 mins online awareness test.

So if you are intrested in designing field then opt NIFT or if you want to make career in architecture field you may go for NATA..

Hope this will help you

Good luckk..