I am studying circle of class $12th$ level. I've come to a concept of pole and polar for circle.
Definition of pole and polar
Let $P$ be any point inside or outside the circle. Draw any chord $AB$ and $A'B'$ passing through $P$. If tangents to the circle at $A$ and $B$ meet at $Q$, then locus of $Q$ is called the polar of $P$ with respect to circle and $P$ is called the pole and if tangents to the circle at $A'$ and $B'$ meet at $Q'$, then the straight line $QQ'$ is polar with $P$ as its pole.
In one book while solving problem I come to know other definition of pole and polar and it goes like:
Suppose $OX$ is a fixed line on which O is a fixed point. Suppose $P$ is a point such that OP=r and anticlockwise angle $XOP$ = $\theta$ , then we define $(r,\theta)$ as polar coordinates of a point $P$, $O$ is called pole and line $OX$ is called initial line.
I want know that are those two definitions represent same thing?
if yes, then will be please elaborate? and if no, then why someone did not name them differently. I just want to clear my confusion.
I am attaching image from my book for reference.