Here's the nutshell - you don't need to know all that, and it would take a couple of years for you study enough to utilize the complex knowledge in any effective way. Do you really imagine that teachers are just told these concepts and then told to go forth and use them without further training?   You need to figure out what works for your particular kid, and you can do that by trial and error. Be patient, try new things, think outside of the box. If you and your kid can't figure everything at once, then just work on one thing at a time. One thing. Be patient.

Psychology is not a settled science and the terms used by believers in different approaches differ.  Sometimes, they partly overlap.  You've just found one of dozens or hundreds of such places.  Don't try to make sense of them, just find out if the methods they recommend work for your son.  discard methods that don't work -- likely there are plenty of these -- and retain ones that do.

That said [and knowing that both of these description methods are long outmoded], concrete and abstract pretend to be opposites, as do random and sequential. these are part of one system of description.  left and right brain are part of a different system.

in general, left brain would relate well to concrete and sequential while right brain would relate well to abstract and random.  This is not an exact pairing and plenty of well meaning special educators and psychologists will disagree with any or all of these statements [some at the top of their lungs, i'm afraid]

To further confuse matters, your son's age likely makes a difference.  Young children tend to require direct experience and guided practice with near everything ... which is why kindergarten is organized the way it is.  Some, but by no means all, teens work well with learning from books in a logical, organized way.  Others still require direct experience and practice.

Atop all of this, some children learn well from reading and doing [Dr. Ben Carson was such a one], others from listening and talking [but schools discourage talking], and yet others from directly manipulating materials and trying things for themselves -- and this can change as the child grows from 6 to 16.

Experience in business enterprises tells me that there are jobs for all types of learners -- and that matching the potential employee to the right sort of work is critical -- both for the prospect's happiness [and thus how long they will likely stay with your firm] and for the functioning of your company.

There is a successful business owner in Britain whose work in this area I reviewed [he consults to other business owners on difficult matters, including personnel issues].  This man set out to catalogue the different "schools" of psychology offering services to businesses in Britain.  He stopped when the number reached 400. [four hundred -- not a typo].

{Ya, you've got me pegged ... I'm pretty logical and sequential.  Give me evidence and let me draw logical inferences from it and everything else I know.  I'm not a "people person" by choice ... I frankly don't emphasize with an employee's tales of woe as to why they're chronically late to work.  If their family is so important that caring for them detracts from their willingness to be here for work ... my customers want someone who will be here and thus I part ways with that person -- they're in the wrong field -- should have been a social worker.}

What you are groping toward doing is not easy, nor simple for many children. Do you per chance have knowledge about the methods that have worked for your son in the past?  If so, start there ... there are plenty of kids that like doing things over and over [just think of the videos they've watched tens of times ... and enjoy them still.]

GL