So I have this page with the menu item type as "categories", which display item list of one category. When one of the items clicked, the item view page wil display, and this page has a same template with the former one.
But I want it to be different. In particular, I want a module on the former page not to display on the item view page, how to do that?
Thanks for any help or hint.

Anyone can answer this? or did I not descripe my question clearly?

Hello Vincent,

I am not quite sure of what you want to achieve here. You want a module shown on the cateogy listing and not in the item?

If I got it right, you should hide the entire module position from items. This snippet will do the trick