Filling in a questionnaire, in different languages, after picking a language up, you get 4 options :
So, how are "fließend" and "verhandlungssicher" different in this context?
The Council of Europe made great efforts to define language skill levels. From this the three classic divisions basic, intermediate, and advanced are further elaborated to give us six levels of skill.
The detailed definitions given (see link above) can roughly be translated as follows
Please note that demands on our language skills may vary from our profession. We may therefore have a different opinion on what level is considered to be "verhandlungssicher", or "fließend". Imagine that you could already actively follow discussions (Verhandlung) from your specialized field in level B2, or on the other hand you may need at least level C1 if you have to fluently communicate with customers.
A language teacher told me once that "fließend" means you are able to express yourself in a foreign language without hesitating and quite naturally. "Fließend" implies less proficiency than a native speaker, but more than "verhandlungssicher". If you are "verhandlungssicher" you do not have to understand everything your counterpart says to you, but you should be able to follow the conversation and ask questions if you don't understand everything he says to you so as to arrive at a common solution when negotiating.
In my understanding
Fließend (fluently) means
Verhandlungssicher (business fluent) means
Fließend : You can master a normal conversation at a tea party.
Verhandlungssicher : You can master a discussion where the people won't necessarily be nice to you and will be speaking much faster.
Basically it's conversation vs. agitated discussion