The word to (as in, to a destination) is a very general term and says nothing about the actual direction or the state of motion. It merely states that, whichever road you take or means you use, you'll eventually arrive at a specific destination.

The word toward specifies plainly the direction you are going and often implies motion in that direction, but not necessarily the destination.

If you are in Nanchang and want to go to Beijing, the destiniation is known (Beijing), but there is no indication of which road you will take. Perhaps by way of Hong Kong; perhaps by way of Shanghai.

If you are in Nanchang and plan to go toward Beijing, what is your destination? Xuzhou? Beijing? Zhangjiakou?