There is no difference in the technical sense. The answer is NO for questions like:
Will the site load faster if it is .com or .xyz?
Will the site display differently if the domain is .win or .net?
Does the domain have to be purchased at the same place as the hosting? The answer is again NO.
The domain and hosting are only connected via NameServers, and that’s it.
The only difference between domains like .win for $1 and, for example, .com for $11 is their price.
Google looks at the extension, i.e., .win or .de, to determine which country to display it to. Of course, in Google Webmaster Tools, you can set the country you are targeting and thus buy .win and mark Germany.
BUT Google still gives priority to the .de domain over any other when it comes to ranking when searched from Germany.
Conclusion: if your website is not important or is created only for a specific group of people, then you can take any cheap domain. Or if you take a domain for testing. But if you want a website that serves for presentation and sales or providing your services, then definitely .de, first of all, because of the ranking and secondly because people are used to .de compared to, for example, .win.