Hey, thanks for bumping this thread, JR!
Anyway, I've my training has mostly been in Seven Star Praying Mantis Gongfu/Kung Fu/Wushu/Quanfa... whatever the hell ya wanna call it -- (cheesy Chinatown accent)
Chinese Boxing! (/accent)
RE: Gongfu/Kung Fu vs Wushu terminology - everything JR said about these terms is correct. Just to expand on what he's said:
Wushu: Literally means "martial arts." What we know as Kung Fu, karate, Hapkido, Ninjutsu, Savante, Escrima, Pencak Silat, Muay Thai etc - it's all "wushu." In Japanese, it's called
Bujutsu - written with the same Hanzi/Kanji as "wushu" and means the same thing. It's a very broad and generic term. Chinese martial arts in general are called "Zhongguo Wushu" which means "Chinese Martial Arts." "Xiandai Wushu" means "modern martial arts" and specifically refers to the more acrobatic/gymnastic form of exhibitionary Chinese martial arts commonly used in the entertainment industry. Amongst many English speaking martial artists, the term "Wushu" is often synonymous with Xiandai Wushu.
Gongfu/Kung Fu: This term simply means "to excel." To alleviate any confusion between traditional and modern Wushu, martial artists have come to also refer to traditional wushu styles as "Gongfu" or "Kung Fu." This term was popularised amongst Westerners by Bruce Lee.
Quanfa: The traditional Chinese term for "boxing" and is a synonym for "wushu" - i.e.: refers to any form of fighting/martial arts. In Japanese it is pronounced as "Kempo," although in the English language, Kempo refers to a specific style of Japanese martial arts known as Shourinji Kempo, which in Chinese is pronounced as "Shaolinzi Quanfa," which means "Shaolin Temple Boxing," as Shorinji Kempo was a martial art created by Japanese Buddhist monks who had studied source materials from the Shaolin Temple in China.
And as JR also pointed out, Kung Fu/Wushu doesn't refer to a single style, but many styles of martial arts which originate from China. e.g.: Praying Mantis, Long Fist, Southern Fist, Five Ancestors Fist, Drunken Boxing, Monkey Fist, Crane Fist, Wing Chun (Yongchun), Hung Gar (Hongjia), Pak Mei, Tongbeiquan, Baguazhang (Eight Trigrams Palm), Xingyiquan, Choy Li Fut (Cailifa), Baji, Taiji, Goroquan etc etc etc... the list goes on. And amongst these styles you have many substyles. For example, amongst just the Praying Mantis styles you have Seven Star Praying Mantis, Long Fist Praying Mantis, Plum Blossom Praying Mantis, Six Harmony Praying Mantis, 8 Step Praying Mantis, Taiji Praying Mantis, Jade Ring Praying Mantis, Shaolin Praying Mantis etc.!
Many faces of Praying Mantis...




Above: (L-R) Taiji Mantis, Plum Blossom Mantis, 6 Harmony Mantis & 8 Step Mantis
And Kung Fu styles can also vary greatly in nature... some styles can be more circular, fluid and deceptively "graceful," such as Taiji, whilst others are more directly physically brutal and rigid such as Fujian styles of Kung Fu -- which are the direct ancestors of Okinawan Karate and thus looks very similar.

Above: Spot the difference! On the left is Wuzuquan (Five Ancestors Fist), a Fujian style of Kung Fu compared to Shotokan Karate on the right. The two styles exhibit striking similarities, due to Karate's lineage from the Fujian (aka Hokkien) province of Southern China.