Billy Joel was in ascendancy in 1975 at the same time as Elton John peaked in the first phase of his globalized career ~ 1975 and John began to wane as he flirted with the disco and soul craze.
Elton John did not re-surface credibly again until ~ 1983 or 1984, but Billy Joel had been keeping the bleachers warm through out that same time with album after album of solid non-disco genuinely talented writing, composing, and performing.
I saw Joel for the first time in Richmond, VA, April 1, 1979. He came out on stage and played a number solo on the piano. Single spotlight. He completed the song, left the stage, and the lights in the Coliseum came up and roadies started making like they were dis-assembling the equipment.
Predictably, a wail, hue, and cry went up from the audience, then the roadies departed the stage, lights went down suddenly, and Billy Joel dashed back out on stage with the single spot light again trained on him and he grabbed the microphone and shouted "April Fools!!!".
Saw Elton John in concert in 1980 -- a shadow of what he was popularly in 1980 vs what he was in 1975. It was obvious. The band, Chicago, was visibly on the wane then too.
Joel and John were eventually paired in presence and prominence from mid-'80s's through the early 1990's.
The two of them eventually went on tour together ~ 1994. My wife saw them perform together at the Meadowlands.
FReegards!
He also wrote one of the best modern anti-’goverment regulation’ songs...
http://www.youtube.com/watch?v=XN4I1od02Dw