Let's label these..
> $$\cdots\qquad\langle 1\rangle\qquad\qquad \langle 3\rangle\qquad\qquad\langle 5\rangle\qquad \cdots$$
>
> * * *
>
> $$\qquad\cdots\qquad\langle 2\rangle\qquad\qquad\langle 4\rangle \qquad\cdots$$
With glide reflections, we can, say, move $\langle 1\rangle$ to $\langle 2\rangle$, $\langle 2\rangle$ to $\langle 3\rangle$, and so on. _However_ we cannot, say, glide reflect $\langle 1\rangle$ to $\langle 5\rangle$, $\langle 2\rangle$ to $\langle 4\rangle$, etc., while keeping $\langle 3\rangle$ fixed even though this is a symmetry of the image because glide reflections do not have any fixed points.
Does that make sense?