This is an interesting question on many levels.  When I think of the HE system in the US, I imagine it to be a conflation of all of your categories: Institutions, curriculum, research, faculty and students, certainly, with student learning at the heart of the system. In the United States, it is becoming more of a project of response to legislation, and this challenges the "heart of the system" as you frame the category -- students, in my imagination.  The question of funding streams is relevant to education as a public project on all levels, hence the increasing involvement of government.  At least in the US, I believe that we are at the doorstep of a shift in how the project is organized, in fact, in how it is concieved, and for what purpose.  Currently, what began arguably as a social project has transformed -- negatively, in my opinion -- to a socio-political project.  It is becoming increasingly clear, however, that the current model does not serve the interests of our rapidly diversifying stakeholders.  A shift must occur in how we establish control and educative purpose.  I fear nationalism and sectarianism, and of course, political control  devolves to that in many ways.  I would be interested in hearing other researchers thoughts on the original question, as well as comments on the trajectory of the project.

This is an interesting question on many levels.  When I think of the HE system in the US, I imagine it to be a conflation of all of your categories: Institutions, curriculum, research, faculty and students, certainly, with student learning at the heart of the system. In the United States, it is becoming more of a project of response to legislation, and this challenges the "heart of the system" as you frame the category -- students, in my imagination.  The question of funding streams is relevant to education as a public project on all levels, hence the increasing involvement of government.  At least in the US, I believe that we are at the doorstep of a shift in how the project is organized, in fact, in how it is concieved, and for what purpose.  Currently, what began arguably as a social project has transformed -- negatively, in my opinion -- to a socio-political project.  It is becoming increasingly clear, however, that the current model does not serve the interests of our rapidly diversifying stakeholders.  A shift must occur in how we establish control and educative purpose.  I fear nationalism and sectarianism, and of course, political control  devolves to that in many ways.  I would be interested in hearing other researchers thoughts on the original question, as well as comments on the trajectory of the project.

In my country back than it was simple, higher education is when the national curriculum ends and students have to pay  more for their preferred education. Now that we have the options of technical,  vocational various skills and professional certifications for those as young as 16, the line is blurred. A question that leads to more questions, interesting question indeed.

Good question! One of the problems with the name 'higher education system' is that is suggests cohesion - probably at the level of policy and planning. But, after working in a few institutions, my experience is that practitioners often feel outside of the system and students are always fighting to understand what the system expects of them. Even those within the system can find themselves at odds with each other - as those who work in HR become frustrated with Marketing and those who deal with enrolment are driven crazy by Government policy changes. I am an educationalist and from my perspective the term 'higher education system' seems to be understood differently by all stakeholders and no-one very totally feels part of the system. Yet the system controls us. I am reminded of Foucault's Panopticon - where control seems to come from our own feelings that, at any given moment, our actions are under scrutiny - therefore we must all act in a certain way. So we call it a 'system' but most people do not feel part of the 'system'. yet the 'system' controls what we do.

An education system could be viewed as a set of resources, and their interrelating variables, that produce education.  The term "education" I defined under "Constructive heuristics ...".  The qualifier "higher" sets up an incomplete dichotomy that can be completed only by specifying a measurable variable that lets one decide "higher" or "not higher" without ambiguity.  Although such a specification is possible, the resulting definition may not respond to how the term is commonly used.

In my country (Germany) there is a set of institutions that are defined to deliver higher education programmes that lead to higher education qualifications. This set is legally defined. So the definition basically is institution-driven. In parallel we have a very strong vocational education system that also offers programmes on higher qualification levels but is not "higher education" according to the mentioned definition but as "tertiary education" or "advanced vocational education". There was an intensive discussion in the context of the development of a NQF how both pathways and their related qualificationa are allocated to the higher levels of the NQF. From my point of view it was a first success for the very popular and high valuated German VET system that the "Meister" (an advanced VET qualification) is allocated on the same level as the university bachelor. So it seems that the understanding of the term "higher education" might change. Also because an increasing number of "higher education" programmes at universities focus more and more on the need of the labour market and include a lot of pracitial experience in their curricula and also enhance direct cooperation with companies. 

Ute has offered a valuable insight into this question; namely, that in some cultures there are legal-institutional definitions.  Of course, when it comes to defining terms, being legal does not mean being correct; i.e., being consistent with the etymology and utility of language. However, those definitions can be valid and useful in their own context, as is illustrated by the example of the successful German VET system based on it.   Ute's concluding observation "So it seems that the understanding of the term 'higher education' might change" illustrates the problem with reliance on such definitions: they are not permanent but can change with each generation of legislators based on the whim and subjective-relative viewpoint of those in that generation who legislate such definitions.  Rather, it would be up to persons educated in the discipline of education, like those who participate in this discussion, to agree on rational, permanent, correct definitions.

Thank you for all answers.

Albert, I agree that the definition is not permanent, and depend on legislator, but also (I think) on participants of the system (that is why I wanted to know opinions of scientist from different disciplines). But formally we still depend on the definitions created in our legislation ;(.

The question "What is meant by higher education system" entails a question about the question: higher than what? From my experience interacting with students at various levels including graduate and undergraduate, I offer a response to the sub-question; viz., higher than educational levels at which students are mainly acquiring and/or interpreting information and not being developed and measured on their ability to rationally interpret and make positive successful use of that information.  This is the line that I would draw between higher and not-higher, independently of any legal definition -- bearing in mind what I wrote earlier in this discussion: "Although such a specification is possible, the resulting definition may not respond to how the term is commonly used."  The latter is a purely statistical issue.