http://davinciautomata.wordpress.com/2007/03/03/introducing-clockpunk/: 'Historical Clockpunk explores how the world would have turned out if certain technological developments that occurred later had happened in the Renaissance and or certain inventions in the time of the Renaissance were created on a mass scale in the time period.Non-historical Clockpunk is set in settings similar to the Renaissance but on alternative worlds, planets etc.'
I'm not sure it is different: maybe a sub-genre.
How is this different than alternative history?
http://davinciautomata.wordpress.com/2007/03/03/introducing-clockpunk/: 'Historical Clockpunk explores how the world would have turned out if certain technological developments that occurred later had happened in the Renaissance and or certain inventions in the time of the Renaissance were created on a mass scale in the time period.Non-historical Clockpunk is set in settings similar to the Renaissance but on alternative worlds, planets etc.'