There is no simple answer.  In general both provide energy equally but
differ somewhat if it is the great bulk of what one eats.  Corn has some
things not in it which make it not as fully nutricious as wheat if eaten
alone or with little else.  If not treated, corn can not provide vitamin b
types which can lead to disorders, often has less protein then wheat and
some other things.  But if one has a varied diet along with the corn then
it is no problem..  A wheat alone or little else diet can have it's set of
problems also but not to the same degree as corn and the solution is the
same, eat various other things along with it.  The breads become the major
energy source and the other things add what the grains lack.