About this topic, I found a very useful blog when searching for "smart casual" and it said the following:
Smart Casual:
- Combination of Business and Casual wear but no jeans, t-shirts or sneakers.
Men:
Ladies:
I think the jeans depend on the kind of fabric, colour and whether it is paired with other smart clothes (in the second picture the pants look almost like jeans) Keep in mind that you never know when you could be upgraded to bussiness, and in that case it's better to be prepared and well-dressed!