What would you find if you compared and contrasted a textbook and an academic journal article in the same field?

Answer 1

Generally, textbooks tend to be written for a broader readership (i.e. students) and are meant to give an overview of an expansive subject that could ostensibly be used for a semester or year-long class. They are the quintessential "secondary source", meaning that they synthesize and organize multiple currently-accepted theories about their respective subjects. Textbooks are great for structuring a basic learning plan for secondary-school or college general education classes. They do have multiple downsides, however: they have to be frequently updated as new research replaces and even refutes old information, and as you probably know, they are quite expensive so this is not ideal; they can be fairly formulaic and traditional, usually foregoing any type of potentially "radical" scholarship for widely-accepted and generally approved ideas about their respective subjects; and they are heavily influenced by the extremely traditional and sometimes even reactionary world of general education writing standards; etc.

An academic journal is a collection of research articles and essays published by professional academics in the field. Academic journals present the cutting edge of research in their subjects, and the work is almost always "peer-reviewed", meaning that other comparable academic professionals and experts have fact-checked, responded, questioned, etc. What you see in a major academic journal is usually months if not years of strenuous, committed research that has been signed off on by the leading experts in a given field. A downside here is that the target readership tends to be other academics and graduate students, so the material is frequently quite esoteric (and perhaps intimidating) as opposed to broad and accessible.

So, to wrap up:

If you are looking for a broad overview, you'll find it in the textbook.

If you want to know what the latest innovations and ideas are in a given academic field, seek out respected academic journals.