To make this question more useful generally:
- What is the difference between those two tags? What is the meaning of each tag?
- When to use which? Possibly use both?
- Or should they be merged and additional tags to clarify things be used?
Here's my understanding:
Clothing is more oriented towards the actual materials used, the tailoring and production.
Note that this could also be gained by adding some other tag that makes it more specific, like "production" or "materials".
While fashion is more oriented to how things finally look and what people used to wear at different occassions.
For this one an "etiquette" tag could clarify things too.