Please consider the sentence below:
This section contains some numbers as well as a description.
In this case it feels like both terms (numbers and description) are of equal importance. The numbers arguably slightly more importance since they are mentioned first.
Now consider this:
This section contains some numbers in addition to a description.
To me this implies that the numbers are now supplementing the description, making the description the most important term.
Since 'as well as' and 'in addition to' are often listed as synonyms, I would like to know if they both assume the terms are of equal importance, or if the latter indeed implies a more important part?
Best Answer
I can't think of a case where "as well as" and "in addition to" wouldn't be treated as synonyms.
Both conjunctions imply that the latter term was more expected or more important, and that the first term may have been less important in the situation described or unexpected to the reader. In your examples, the writer is calling attention to the fact that the section contains numbers, and not just a description as the reader might expect.
If both terms were equal, you should simply use "and" as the conjunction.