While a computer program is generally a set of instructions (source, or object code) that perform a specific task, a software system is more or an encompassing concept with many more components such as specification, test results, end-user documentation, maintenance records, etc.
A software system consists of several separate computer programs and associated configuration files, documentation, etc., that operate together.
Software systems are an active area of research for groups interested in software engineering in particular and systems engineering in general.
[4] The ACM Software System Award is an annual award that honors people or an organization "for developing a system that has had a lasting influence, reflected in contributions to concepts, in commercial acceptance, or both".
[5] It has been awarded by the Association for Computing Machinery (ACM) since 1983, with a cash prize sponsored by IBM.