What are angles that are always congruent
Complementary and supplementary angles are always congruent. A linear pair is also known to be congruent. You can check out http://www.regentsprep.org/Regents/math/geometry/GP5/LAngles.htm for details.
they are the same
congruency means that they superimpose each other perfectly so same angles would be congruent , for triangles there are certain theorems related to congruency