1, facing each other means moving in the same direction.

2, relative: it is a face-to-face movement.

Second, the differences in mathematics:

1, mathematically opposite: it means starting from the same place and driving in the opposite direction, resulting in further and further distance.

2. Mathematical relativity: it means starting from A and B and driving towards the center. So, we got closer and closer until we met;

Third, it is applied in different places.

1, opposite direction: when expressing the same goal of both parties, the word opposite direction is often used. In the narrative of political and diplomatic issues, it is often used to express that both sides have the same goal or the same vision and insight.

2. Relativity: Relativity is an abstract word, which means that a substance or a whole is compared with another substance or another whole, or that its existence or change depends on certain conditions.