As we can notice by watching Game Of Thrones' episodes, White Walkers and the dead men are not the same, they have so many differences, can you please mention those differences, and why that the White Walkers are so much stronger than the Wights?
White Walker's are an ancient race. They are powerful enough to manage hand-to-hand combat easily with a human. Normal swords can't kill or harm them. They have only two known weaknesses: Valyrian steel (dragonsteel) and Dragonglass (obsidian). White Walkers can communicate using a laguage known as Skroth
Wights (or dead men or the Army of the Dead) are the minions of the White Walkers. They are like zombies and they can be killed only by burning them and are shown to be highly flammable. White Walkers can even revive corpses and turn them into Wights. Unlike the White Walkers, they're unable to talk and have a far lower intellect.
Note: In the books White Walkers are also referred to as The Others. For more detail, refer to the Wiki pages linked.