はもちろん・はもとより: the difference
はもちろんN3
Meaning
Not only but also, Let alone, Not to mention, Of course
Past papers
Tested once in past papers
Example
平日はもちろん、土日も働いている。
I work not only on weekdays, but also weekends.
はもとよりN2
Meaning
Not only... but also, Let alone, Of course
Past papers
Tested once in past papers
Example
速く走るのはもとより経済的でもある車を買いたい。
Not only a fast one, but I want to buy a car that's also economical.
How to tell them apart
「はもちろん」: plain, fine in speech and writing. 「子供はもちろん、大人も楽しめる」 (Kids, of course, and adults can enjoy it too).
「はもとより」: elegant written style for formal announcements.
「どころか」: a contrast, 'let alone A, not even B' or 'not A, but the opposite', unlike its 'and also'.