What is the difference between Gradient Descent method and Steepest Descent methods?

In this book, they have come under different sections:

http://stanford.edu/~boyd/cvxbook/bv_cvxbook.pdf

According to page 480, Gradient Descent is:

$$\Delta x=-\nabla f(x)$$

While page 490, for Steepest descent says:

$$\Delta x_{sd}=||\nabla f(x)||_*\Delta x_{nsd}$$ $$\Delta x_{nsd} = \text{argmin}\{\nabla f(x)^Tv~|~~~ ||v||\leq 1\}$$

I cannot understand their difference. How they are mathematically and geometrically different?