ASA means angle, side, angle, while AAS means angle, angle, side. These are two ways that decide if a triangle is congruent. It is all a part of geometry. ASA means two triangles are congruent if they have an equal side contained between equivalent equal angles.
If the pinnacles of two triangles are one to one correspondence such that two angles and the involved side of the second triangles, then it meets the stipulation that the triangles are congruent. It is because the angles and the included side are equal in both triangles; this means that the triangles are congruent. AAS means two angles are on different sides.
The non-included side is the side opposite to either one of the two angles being used. Two pairs of corresponding angles and sides opposite to them are equal in both the triangles. The main variance between the two congruence rules is that the side is not included in ASA.