Ferdinand Saussure’s theory places culture first. He states that the mind is a blank canvas before your mind fills it with a set of learned behaviours , rules or habits. Says that sounds form words which he then refers to as the signifier , which through learned behaviour connects our mind to the object being the signified.
Signifier being the sounds of the letters used to denote what we are talking about, signified being the concept of the thing we are talking about.Referent being the real thing in the world.
Saussure states that the relationship between the signifier & the signified is arbitrary. Arbitrary is based on random choice or personal whim, rather than any reason or system.Got an Example of a dog , there are several different words for dog through different languages, yet if in England we started calling a dog a cat, no one would know what we where going on about.
We all have different quirky sayings for different things, they may be culturally local to where your from. This is called Diachrony , slight changes in abbreviations though time.
Being able to determine the difference in theories, an who represents them, is a great help, as can now feel at ease to apply them to work.