Re: DP 8.0 -what is the difference between DP 7.0 and DP 8.0？

Rather than offer a long, and probably an incomplete explanation here, I suggest that you read the Product announcements guide for DP 8

http://support.openview.hp.com/selfsolve/document/KM00452466?searchIdentifier=3cb88a9%3a14111990a00%3a-40ea&resultType=document&documentURL=KM00452466&resultsURL=%2fselfsolve%2fmanuals&allowReturn=true&searchString=&searchKey=2013-09-12+03%3a06%3a12

There have been a number of challenges with upgrading to DP 8, and I recommend that you wait until at least, the first set of patches come out