As stated earlier and by Ishan, there is gap in the implementation.
You are not setting s.prodview event on every s.t() call of your Product Details Page and thus you see that Page Views were higher than Prod Views. Make sure that your Business Logic to capture Product Views is based on Page Views and if so, fix the implementation because Business requirement might omit reloads or post page load s.t() calls.
The numbers of Page Views and Product Views would depend on the implementation. Page Views are counted when there is a s.t() call triggering to Analytics. Product Views, on the other hand, are counted whenever s.prodView is triggered as an event in s.event variable.
If s.prodView is always fired with the page view call on the Product Details page, the numbers would be same. However, it doesn't seem to be the case here.