This Maine Dept of Transportation article contains an excellent summary comparison of Speed Bumps versus Speed Humps which is presented here.

Speed Humps:

• Are a gradual raised area in the pavement surface extending across the entire travel width
• Typically, 3 to 4 inches in height with a travel length of 12 to 15 ft
• Have evolved from extensive research & testing
• Create a gentle vehicle rocking motion which results in most vehicles slowing to 15 mph at each hump and 25 to 30 mph between properly spaced humps in a system
• Need to be designed and installed with proper planning and engineering
• Effective at controlling speeds without creating accidents or imposing unreasonable or unacceptable safety risks

Speed Bumps:

• Are an abrupt raised area in the pavement surface
• Effective at controlling speeds on low volume, low speed roads, especially private driveways & parking lots
• Typically, 3 to 6 inches in height with a travel length of 6 in. to 3 ft
• Cause significant driver discomfort at typical residential speeds.
• Cause vehicles to slow to 5 mph or less at the bump.
• Maintenance headaches especially for plow trucks.

And as always… beware of speed bumps on the road of life!