When it comes to the way that people use language to identify ideas and concepts, syntax and semantics play two different roles and mean two entirely different things. Where syntax addresses the way that words or phrases fit together in a sentence, perhaps even semantically, semantics is the study of each individual word, icon, or symbol, and how it is perceived by the mind. Knowing the difference between these the core concepts of syntax and semantics can benefit anyone involved in the human sciences related to language or communications.
To understand the difference between syntax and semantics further requires a developed comprehension of each of these two "data types" or "cognitive protocols". The first one, syntax, is related to the grammar, phrasing, punctuation, and other elements of a language that influence exactly how people use and understand that language. For example, considering how phrasal verbs are made up of a simple verb and a simple preposition is a syntax issue.
An example of semantics is a juxtaposition of two symbols or verbal/visual elements. Humans make choices about the interpretation of semantics based on fixed associations and learned associations. Semantical context may be important, for example, in manufacturing consumer goods that use symbols to communicate to a worldwide consumer base, rather than using the words and conventions of a single nation.
To further define semantics, experts often talk about the connotations of words and symbols as the pursuit of semantics. Semantics still relates to the idea that units of speech have meaning, and it can apply to either a single unit or the linking of two units. Some academics and others refer to fields like philology that study the use of words or ideas as being semantical in nature.
Both syntax and semantics are useful in the general realm of linguistics. To distinguish the common roles of both syntax and semantics, an academic might use syntax to study whether linking of words is correct, and semantics to figure out generally how multiple words are perceived when presented together in any given order. Linguists can use a combination of semantic and syntactical study to build language models for many different research uses. These may also figure prominently in research proposals that aim to further define practical uses of known language structures.