An addition is something added to what was already there: "the conservatory is a recent addition to the house". An edition is one particular version or printing of something published or produced: "the second edition of the textbook", "a limited edition print". Swap in extra for addition and version for edition.
The core difference
These two are unrelated in meaning and only collide because they sound alike in rapid speech — the opening vowels blur, and the rest of the word is identical.
Addition belongs with add. It is the act of adding, the thing added, or the arithmetic operation: the addition of salt, a welcome addition to the squad, she is good at addition and subtraction.
Edition belongs with edit. It is one issue or version of a published or manufactured item: the paperback edition, Tuesday's edition of the paper, a special edition trainer.
The test you can run
Try both substitutions on your sentence:
- Does extra or something added fit? → addition. "A welcome extra to the team" makes sense, so a welcome addition to the team.
- Does version or print run fit? → edition. "A limited version" makes sense, so a limited edition.
The spelling hook follows from that: addition starts like add, edition starts like edit. If nothing is being added, the word is not addition.
Where writers go wrong
By far the most common error is limited addition, which turns up constantly in online listings and marketing copy. A limited edition is a restricted print or production run — nothing is being added at all. The same slip produces first addition for first edition and, less often, a new edition to the family for a new addition to the family.
The other trap is the phrase in addition to, meaning "as well as": In addition to the deposit, there is a booking fee. This never takes edition, and it is one word too many if you already wrote also — pick one.
The edge cases
Both words have technical senses worth knowing. In publishing, an edition is not the same as a reprint: a new edition has revised content, while a reprint is the same text printed again. Broadcasters also use edition for a single instalment of a programme — tonight's edition.
In building work, an addition is an extension to a structure, particularly in American usage: they built an addition at the back. British writers would more often say extension, but addition is not wrong.
