Please have a look on the following example of mine and let me know whether my conclusion is correct or I have to know something else about this specific topic:
- The library on 5th Avenue in New York City is one of the best places to do research. ……………… it has hundreds of the most respected magazines and journals in the world.
c) in addition
e) as well as that
f) on top of that
For me all of these adverbs can be used in the blank above and they all add new information to what is already known and consequently can easily be swapped everywhere.
In summary, for me:
1) All these adverbs mean the same.
2a) Moreover = Furthermore = In addition = Additionally ==> All are formal and can be swapped with each other everywhere freely
2b) As well as that = On top of that = Besides ==> All are informal and can be swapped with each other everywhere freely (therefore cannot be used e.g. in a business formal letter.)