Silicon Valley is not about ideas or just tech-companies, is about investors and culture. In Europe experimenting is very very difficult, I worked on a project involving big data, predictions and very advanced live stuff that at the moment are hot in SV, but in Europe investors look not interested or ready to support this field. Another huge problem is the poor ability of European investors in following the tech-trend. 6 months ago I did a presentation about a product I was working on, looking for fundings, it was for one of the biggest VC/Incubator (focusing on medtech, green energy and hi-tech) in Switzerland and at the of the presentation I have been asked by the president what "a phone notification is" and "what is bluetooth LE", so I spent my QA time answering basic questions about the current technology instead about the product I was working on. I know not all European VCs have a similar mindset, but the general importance order for an European VC is: intellectual property protection, amount of money required to release, high market barriers looking for no short-term competition and, lastly, shipping time.
An American investor doesn't care too much about competition, as long as the company provides a far better service (with a clear real advantage) this is not an issue, IP is important, but only if the product gains traction and goes mainstream (so it means $ that mean patents), the amount of money as well is not an issue, with so many VCs you can manage to get all necessary fundings if the product is valid, so what really matter is entering in the market as soon as possible with something that is good enough. These are just few examples I faced, but there are many other differences...