As far I am aware the difference between NAAB and ABET is essentially the field of post-secondary educational programs they accredit in the USA and abroad. NAAB accredits the programs in architecture whilst the ABET accredits the programs in applied and natural science, computing, engineering and engineering technology.
In a way it is similar to the approach in the UK where there is a split between the academic and professional qualifications. For example, one can gain an academic qualifications in architecture (e.g., BA, DipArch, BArch, MArch or similar) from an UK university or a college, but on its own it would not be valid for entry into the profession as an architect unless the actual program completed is also accredited by the ARB (Architects Registration Board) and/or RIBA (Royal Institute of British Architects). Therefore, in order for someone to be able to practice legally in the UK as architect the person would have to be Registered Architect with the UK Architects Registration Board.
This link leads to the UK ARB accredited programs in architecture:
They can be essentially accredited at three different levels:
Part 1 which is typically an accredited BA program
Part 2 which is typically and accredited MArch program
Part 3 which is typically an accredited Exam in Professional Practice in Architecture and Management.
One has to have all three Part from ARB accredited programs in order to become architect. This is just an example of how things are done in the UK. i believe that a similar principles applies in USA too.
You may follow the discussion under https://www.researchgate.net/post/Did_ABET_change_the_directions_of_Architectural_Design_Studios_in_the_USA_or_elsewhere