There are some styles can be grouped under one denomination. Jacquard for example indicate all the styles made on the double cylinder machine, using 2 colours, one on front and one on reverse. It means you have two threads (or four, if the yarn enter double thread each side) of two different colours : the design is made playing with the two and having one up and one down in order to make up the pattern.
Looking at the sock inside out, you have exactly the same design on reverse, just with reversed colours. This kind of pattern is called Jacquard from the name of the French inventor of the first flat machine using this kind of procedure.