Thread:B214/@comment-112.198.102.112-20170222052736

Why can Vali activate Diabolos Dragon which is according to wiki, was unique to Issei?

Diabolos Dragon  ( Ｄ×Ｄ ディアボロス・ドラゴン , Diaborosu Doragon ): Is a form that is exclusive to Issei. This is due to the fact that his body is made from Great Red's flesh, which enables Issei to temporarily borrow Ophis' power.

If they are different, then what is/are the difference/s?  