Hi Ostin

TNEA or Tamil Nadu Engineering Admission is for B.E./ B.Tech programmes in which there is no entrance exam. You only need your qualifying exam marks (10+2 or equivalent) for TNEA. 

TANCET or Tamil Nadu Common Entrance Test is an exam for admission to M.E./ M.Tech programmes offered by colleges of Anna University. The admission will be on the basis of GATE or TANCET scores.

So, the level of difficulty for both admission/ exam cannot be compared as one is at the undergraduate level and the other one is at postgraduate level.

Hope this helps you.

All the best!