FACTBOX: Michael Phelps v Mark Spitz

(Reuters) - Following is a comparison between swimmer Michael Phelps, who broke the record for the most gold medals at a single Olympics on Sunday, and the previous record holder Mark Spitz:

- Both swimmers are American. Phelps was born in Baltimore, Maryland, and Spitz in Modesto, California.

- Phelps comes from a broken home. His policeman father Fred and school teacher mother Debbie separated when he was seven. Elder sister Whitney, also a swimmer, has written that she used the swimming pool as a refuge from the yelling.

Spitz was born in California but his family moved to Hawaii when he was two. There his father Arnold taught him how to swim. They returned to California when he was six.

- Phelps attended the Sydney Olympics in 2000 and was 19 when he went to the 2004 Games in Athens. He won six gold and two bronze medals.

Spitz was 18 when he went to his first Olympics, the 1968 Games in Mexico City. He had predicted he would win six golds but ended up with two (both in relays), one silver and one bronze.

- Phelps is 23 at his second Olympics in Beijing. He won eight golds and set seven world records.

Spitz was 22 for his second Olympics, the 1972 Games in Munich. He won seven gold medals, breaking the world record in each event.

- Phelps comfortably won six of his eight golds and nearly missed out on two. He edged out Serbia's Milorad Cavic by 0.01 seconds in the 100m butterfly while the American 4x100m freestyle relay team finished ahead of France by just 0.08 seconds.

Spitz was not pushed so hard. His closest test in Munich came from fellow countryman Jerry Heidenreich who trailed him by 0.43 seconds in the 100m freestyle.

- Phelps is bigger, heavier and wider than Spitz at 1.93 meters tall, weighing 91 kg (79kg) and with an arm span of 2.01 meters.

- Spitz was famous for his bushy moustache. Phelps and other male swimmers now shave their body hair to reduce drag.

- Marketing experts estimate Phelps will become the richest professional swimmer ever, far surpassing the money earned by Spitz. He reportedly earns about $5 million a year from endorsements and one brand strategist says that could rise to about $30 million in the short term.

Spitz endorsed a wide range of products including milk, hairdryers, watches and men's underwear. Marketing experts say his appeal quickly waned, partly because he endorsed too many products. He still earned a reported $5 million, making him a pioneer of athletic endorsements.

(Compiled by Nigel Hunt; editing by Robert Woodward)