Colony and empire, colonialism and imperialism, are often treated as synonyms. This can be acceptable for many purposes. But there may be also good reasons to distinguish between them. This article considers in detail one important attempt in that direction by the classicist Moses Finley. It argues that there is considerable strength in that approach, putting the stress as it does on the distinctiveness of the settler community. It is also valuable in suggesting that early-modern Western colonialism marked a new departure in an older history of imperialism, thus once again suggesting the need for a conceptual separation of the two. But the article concludes that ultimately more may be lost than gained by insisting on the distinction. In particular, it inhibits wide-ranging comparisons between ancient and modern, and Western and non-Western, empires, which can often suggest illuminating connections and parallels. The field of empire studies gains by drawing on the rich store of examples provided by the whole history of empire, from the earliest times to now. Western colonialism is part of that story; to separate it out is to impoverish the field.