Hi Hyun,
They has several different for catalog and content.
1. you only can use SQL script in SP for catalog, but you can create visualization SP in content(for example, create input and output paramter in perspective).
2. you can define appointed schema of SP in catalog, but you can not define schema in SP of content, it is default in schema(_SYS_BIC) so far.
We created SP in catalog basically, generally, it was created based on customer and your project strategy or policy, if customer or project ask you to create SP in appointed schema not _SYS_BIC, I think that you only can create in catalog , besides, consider develop and maintain efficient and cost, it may uses catalog way, it is only my opinion.
Hope this can help you.
Regards,
Jerry