The tag wiki excerpt for code says:
Concerning computer code written or used in the context of a research project or other academic endeavor. Includes questions on licensing, ownership, sharing, distribution, and formatting of academic source code
Questions with this tag are specifically about things having to do with the source code itself, like
- Study of code share practices in science
- Advisor professor asks for my dissertation research source code
- How to submit code (visual studio projects, C#, OpenCL) with my IEEE paper submission
The tag wiki excerpt for software says:
Queries related to various software used in academia. Questions shall not address highly technical aspects of the software but shall address features/issues highly relevant to academia.
Questions in this tag should be about the software, not the code, like:
- Software for extracting data from a graph without having to click on every single point?
- Lab colleague uses cracked software. Should I report it?
- Popular proprietary program or obscure open source substitute for reproducible research?
These seem like distinct tags to me - I don't see any benefit in combining them.