additionally

The word “additionally” means as a further point; also. In plain terms, a more formal way of saying "also" or "on top of that.".

Here is “additionally” used in a sentence: “Additionally, the report notes a rise in costs.”

“Additionally” is an adverb.

“Additionally” is a fairly common word in modern English, usually learned at around the B2 level.

Both add a further point, but additionally is more formal and usually opens a sentence, often followed by a comma, as in "Additionally, the report notes..." Also is shorter and more flexible, fitting comfortably in the middle of a sentence. Additionally suits formal writing, while also works everywhere.

The two are very close in meaning, both introducing a further point. Additionally is a single adverb, while "in addition" is a phrase that can stand alone or be extended to "in addition to" before a noun. "In addition to the fee" is correct, whereas additionally is not used with "to" in that way.

Additionally most often begins a sentence and is followed by a comma, signalling that another point follows the previous one. It can also appear mid-sentence, as in "The plan is, additionally, quite costly," set off by commas. It is a linking adverb, so it connects ideas rather than acting on a specific noun.

Additionally leans formal and is common in reports, essays, and business writing. In casual conversation people are more likely to say also, plus, or on top of that to add a further point.