IQueryable<Ad> list1 = db.Ads.Where(x=>x.isModerated == true);
IQueryable<Ad> list2;

if(something == true)
   {
      list2 = list1.Where(x=>x.TypeId == 2)
         // is it going to be the same as query below?
            IQueryable<Ad> list1 = db.Ads.Where(x=>x.isModerated == true && x.TypeId == 2)
   }