A compiler translates an entire program’s source code into machine code before execution. This machine code is stored in an executable file, which the computer’s hardware can run directly. Compiled programs typically run faster since the translation occurs only once. Errors are identified during the compilation process, meaning the program must be error-free to execute. Examples of compiled languages include C and C++.

In contrast, an interpreter translates and executes the source code line by line at runtime. This real-time translation results in slower execution since each line of code is interpreted on the fly. Errors are detected during runtime, allowing the program to run until an error occurs. Interpreted languages include Python and JavaScript.

In summary, a compiler translates the entire code at once, resulting in faster execution and pre-runtime error detection, producing an executable file. An interpreter translates code line by line, leading to slower execution with runtime error detection and no intermediate machine code file. Some languages, like Java, use both compilation and interpretation, first compiling to bytecode, then interpreting or using just-in-time (JIT) compilation for execution.