The 78 is yours that you've earned, while the 27 has been delegated (loaned) to you for use until you reach a certain level, at which point it'll likely be taken away (mine was taken away when I reached about 480 SP I think, which, consequently was when I got my voting power slider bar as well). I think I was delegated 145 Steem as SP but this was before the Hard Fork, so it didn't help me that much. Then when the Hard Fork happened my vote was worth 53 cents, but the value of steem was almost $3 back then. Now my 100% vote is around 20 cents. Hope this helps!