Difference Between Transpiler and Compiler

A compiler is a software that converts high-level language to low-level assembly language and we are all quite familiar with its name and work. A transpiler is another software, sometimes called a source-to-source compiler, which converts a high-level language to another high-level language. It is immediately not clear why we would need a transpiler and when we can recode the program into another language. 

The reason we need a transpiler is that recoding a large program into another language is time-consuming. engaging an entire developer team in recoding the whole software in another language, with no added improvements, is economically inefficient. Hence it is better to write a language-to-language transpiler that does the job. The Javascript transpilers essentially do the same thing. Web browsers cannot compile TypeScript, CoffeeScript, or Kotlin natively and we need a transpiler for converting them to Javascript.

If to read every foreign research paper, we had to understand the foreign language, then it would take a lot of effort. Life without a translator is hard, and so is without a transpiler. 

Compiler: Compiler is any program that takes as input a source code written in a language and converts it into an output code in some other language, usually with a lower level of abstraction. In practice, compilers convert codes written in high-level programming languages, with a greater abstraction to the machine but more readable to humans, into assembly language, which are low in terms of machine-level abstraction, and readily convertible to binary machine codes but offer little human comprehensibility. 

Transpiler: Transpilers also convert an input source code written in some language into an output code in a different language, that has a similar level of abstraction as compared to the source code. Transpilers are source-to-source converters. They convert codes from one high-level language, say Java, to another high-level language with a similar level of abstraction, say C++. This output is still abstract to the hardware and needs a compiler to convert into assembly language to run on the machine.

Difference between Transpiler and Compiler:

Compiler	Transpiler
It converts a source code written in a high-level language to an output code in a low-level language.	It converts a source code written in a high-level language to an output code in a different high-level language.
The source code has a higher level of abstraction than the output code.	The source code, as well as the output code generated, are of the same level of abstraction.
Output code is in assembly language and is readily executable after linking and decoding into machine language.	Output code is still in high-level programming language and requires a compiler to convert into low-abstraction assembly language.
In a compiler, the source code is scanned, parsed, transformed into an abstract syntax tree semantically analyzed, then converted into an intermediate code, and finally into the assembly language.	In a transpiler, the source code is parsed, and transformed into an abstract syntax tree, which is then converted to an intermediate model. This then transforms into an abstract syntax tree of the target language and code is generated.
Converting Java code into assembly language instructions is an example of compilation.	Converting Java code into C++ code is an example of transpilation.