Object code and machine code are closely related but serve distinct purposes in the software development process. Here's a concise explanation of their differences:

1. Object Code: It is a partially compiled code generated by a compiler or assembler. Object code is not yet a complete executable program. It often contains placeholders or references (e.g., unresolved symbols) that need to be linked with other object files or libraries. It is typically stored in object files (e.g., .o or .obj files) and may include metadata like relocation information and symbol tables. Object code is machine-readable but not directly executable until linked.

2. Machine Code: It is the final, fully compiled code that the CPU can execute directly. Machine code is in binary format (1s and 0s) and contains no unresolved references or placeholders. It is the output of the linking process, where all object files and libraries are combined into a single executable file. Machine code is specific to the target hardware and is ready for execution by the processor.