I think the comparsion between u2 and jovi during the early nineties have to with achtung baby and kft with both of them being landmark albums during the grunge area. I don't think it has nothing to do with the actual music but more with the stylistic change by both bands in their musical direction. Achtung came out in early 91 and KTF in nov 92 almost two years later. I think the reference by jovi being influenced by u2 during ktf is about taking chances musically/ change in direction/vision of the band/evolution of the band's sound and songwriting. U2 did it first with Acthung and Jovi followed later. Both albums were hugely successful worldwide.