Traditional kung fu encompasses hundreds of family styles with a legendary history spanning thousands of years. Wushu was created in 1949 by the People's Republic of China for the purpose of sport, exhibition and control. After all, you can't rule a communist government with all those empowered Chinese families.
Both systems are considered kung fu, one contemporary the other ancient. Excellence in either requires very high levels of athleticism, dedication, training and time. Their purpose however is dramatically different. One is sensational, the other lethal.
Kungfu translates to, "great skill acquired through hard work over a long period of time." You can have good kung fu in your long time profession or as a parent of teenagers. It is not isolated to the martial arts.
Wushu translates to wu = martial, shu = art. This is a general term the Chinese use.
Let's be clear, what you see in movies, on Broadway and in promotional material is not the kung fu of legend. Martial artists flying over bamboo forests and performing gymnastics entertain and generate income for the government. This is in sharp contrast to the faceless masters that have preserved their family style in the dusty shadows, out of sight of oppressive rule. Don't be fooled by what is offered in mass media. Powerful governments secure tight control over global perception so much of the real people's voice is never heard.
The question becomes, "why do you want to study Kung fu"? If you seek a realistic method of self-defense, a system so safe you can practice it well into old age and optimize your health inside and out, well then traditional kung fu is your answer. If you seek gymnastics, competition and speed, then Wushu is for you. It will be joining the ranks of Olympic Sports in 2022. Notice it is coined as a sport, not art, because the development of character is not a fundamental virtue like in traditional Kung Fu.
Traditional, pure lineage based Kung fu is becoming a rarity. It's not due to one being better than the other. It has many reasons, but mostly, history and time. The real Masters of China were oppressed, ousted and practically wiped out by the People's Republic of China. Many Chinese were not inclined to share their art with foreigners.
There are myriad of reasons, but the bottom line is that it is not aligned with the American mentality of "just add water."
Here are some tips to use when seeking traditional training. How long have they been operating? Is the lineage of the Sifu valid? Is the style authentic or created by combining several? What are the students wearing? (you'll often find them shoeless and wearing karate uniforms), which is Japanese - beware) watch a class to observe intent and structure of training.
Remember, there are many self-proclaimed Masters, so do your homework. These "false monks" are generally Masters of bullshit and marketing. This art form that can transform your life so take your time and choose wisely. Good luck.