Pad and iPhones display pictures by “date created” which is not necessarily the same as “date taken”. Basically all pictures start with a creation date based on the date the picture was taken however if the picture is saved under a different name or is copied, a new “date created” will be established in the metadata. Unfortunately in iOS you don't have the options available in OS X or Windows to sort pictures for display. To display the pictures in your iPad in the order you want to see them try the following:
1. In your PC’s File Manager create a new folder under My Pictures and name it as you wish, lets say Vacation. That name will be the name that will show up in your iPad.
2. Delete the iPod Photo Cache folder (if there is one) under My Pictures (iPod is correct, not iPad). Usually a new gets created with every iTunes sync.
3. Copy, not move, the pictures you want into the Vacation folder one by one in the order you want them displayed in your iPad. By copying each picture in the right order a new “date created” with be established in the metadata of the photos.
4) If you want to see the pictures in your PC in the new order, select View > Details and sort by “date created”. If “date created” is not shown in the header, right click on the header and tick “date created” in the drop down menu. Go back to "View" and select “Icons” and you will see the pictures in order.
5) Open iTunes and sync the Vacation folder to your iPad (make sure the folder you had synced previously is not also selected, that way it gets deleted). The pictures will now show up in the order you want, essentially any order that you chose if you copy them in that order. This works for iPhones as well.