去 = go, does not specify the mode how you do it.
走 = walk or run (classical Chinese, 走馬 (running horse) 走狗 (running dog i.e. traitor, someone's lackey etc, 走火[入魔] (running fire, a technical term used in physciology/tcm), 走水 (running water, a euphemistic way of saying there's a fire broke out in the palace, to avoid the tabu word of fire)