Coochycool, the A-7 was the ground-attack version of the F-8 - it could carry over three times the weight of ordnance (15,000lb vs 4,000lb - 3 pylons under each wing instead of 1 helped in this), and carry it further.
It also could navigate its way there & back better, and hit its intended targets with much greater accuracy.
It also entered front-line service some 10 years after the F-8 did.