I would say that the Knight of Wands' movement is motivated by wandsy stimulators - passion, adventure, athleticism, frustration, the "travel itch," and his you-know-what! So what gets him moving are the aforementioned wandsy drives. This is the guy (or gal) that is the adrenaline junkie, and the guy that has "ants in his pants" and is always searching for new scenery. This is the guy that always has the urge to visit different places. He loves spontaneity. He loves getting "turned on!" - whether that's through hot new hookups every weekend, zip lining in Mexico, or kicking some a** in karate class!
The Knight of Swords, on the other hand, is motivated by swordsy stimulators - drive to seek truth, justice, debate, and conversation. He will speak his mind whether you like it or not, defend his views, and speak up for the voiceless. He loves a good healthy debate, but because he's not as refined as the King, there is a lot of rawness and harshness behind his words - this can hurt someone, effect big changes, or cause some major heated arguments. Either way, his ultimate goal is to get people thinking and hopefully change their minds. I actually do like the Knight of Swords in love because I am someone who enjoys a good, healthy, stimulating conversation. And I find that the Knight of Swords always pops up when I find me guys that fit that bill.
Ultimately, they are both impulsive, but I believe they are stimulated by different motivators according to their suit.