I understand that:

`atan2(vector.y, vector.x)` = the angle between the **vector and the X axis**.

But I wanted to know how to get the angle between **two vectors** using atan2. So I came across this solution:

```
atan2(vector1.y - vector2.y, vector1.x - vector2.x)

```

My question is very simple:

Will the two following formulas produce the same number?

* `atan2(vector1.y - vector2.y, vector1.x - vector2.x)`
* `atan2(vector2.y - vector1.y, vector2.x - vector1.x)`

If not: **How do I know what vector comes first in the subtractions?**