The only similarity between Kevin Keegan and Howard Kendall is that both came to their respective club as a player and later became manager.
Howard Kendall, a Geordie lad born on May 22, 1946 in Ryton, Tyne and Wear, has an uncle (Harry Taylor) who played for Newcastle United and Fulham in the 1950s.
But Kendall made his name famous at Everton with whom he signed in March 1967 in a £80,000 transfer. Originally playing as a defender, Kendall was moved into midfield with Alan Ball and Colin Harvey.
In May 1981 Kendall returned to Everton as player-manager, and performed in four games before finally retiring from his career on the field. He struggled as a manager and was on the verge of being sacked in January 1984. In 1987 he left Everton to manage Athletic Bilbao in Spain.
He turned down an offer to manage Newcastle United in 1989 in order to remain in Spain, but was then sacked in November 1989. The following month he returned to England as manager of Manchester City, then returning to Everton in November 1990.
Kendall was less successful the second time around, resigning in December 1993 after a row about money and signings. Following a series of stints managing of other clubs (Xanthi, Notts County, and Sheffield United) he made a third return to Everton in August 1997, but resigned at the end of the season having only managed to avoid relegation on the final day of the season.
Kendall's second return to Everton was initially because the board had no back-up plans. King Kev, on the other hand, returned as the manager of Newcastle United because he was chosen by the board and owner. King Kev will have all the support (financial and otherwise) needed to sign any player he likes.
Additionally, I don't think Kendall has a close relationship with the Everton fans—despite his "Holy Trinity" with Ball and Harvey—while Keegan shares a real soul connection with the Toon Army.
I know it's too early to tell if Keegan's second attempt as manager of Newcastle will prove more successful than the first, but with significant back-up from Mike Ashley and with some luck he will make it this time. He has unfinished business at Newcastle: bringing silverware to Newcastle United.