I was asked: what are the differences between the study of English (the language), English literature and English linguistics? I can only attempt an answer as a layman practitioner, not as someone who had taken academic courses in the different areas of English Studies. I attempt the "fools rush in" exercise below with the caveat that I might be writing nonsense.
To me, the starting point is: what is language? It is a means of communication, artistic expression (Wikipedia) and "record keeping". It is hence both spoken and written. Without going into how the English language arose and evolved into the various "Englishes" that exist today, and their continuing adaptation, we might note that:
* there has to be rules, from that broad category referred to as grammar to specific areas such as linguistics (for example, speech sounds and non-speech sounds) and language meaning (for example, semantics).
* one can "learn English" through a formal step by step process, as is done through, say, the school system and adult education programmes.
* but one can also be immersed in it and, I suppose, learn English through "trial and error".
* English is, fortunately, not a multi-tonal language but it has its pitfalls for the learner (and even its practitioner) since many of its rules are not consistent.
To come back to the question posed to me, I would say that:
* the study of English up to the secondary/post-secondary school level is principally (but not exclusively) for the purpose of communication and includes the basic rules especially of grammar and phonetics, as well as the study of literary works (including poetry, theatre and drama) which is meant to impart reflection and analysis.
* beyond the secondary/post-secondary level, the study of both linguistics and literature goes in-depth (a rarefied group presumably delves deeper into the grammar and other aspects). Indeed, a university Department of English and Linguistics typically expects its students to be already proficient in the language and, beyond the requisite "101" modules, to go on to attain a high level of skill in discourse, research, analysis and critique.
* I should add that those who intend to teach English will require training in the language's pedagogy, that is, instructional methods.
Having said all that, one should always have fun with the English language. It is never boring, even if it is often infuriating. Exhibit A below has been making the rounds online: