Originally the French form of the more learned Magdalene and Anglicized as Madeline. However Madeleine is now the more popular spelling in English communities. The origin is Hebrew, "woman from Magdala", a village by Lake Galilee.

ONC gives a number of spelling variations: Madoline (common in Ireland) and Madlyn, both of which are rare, and Madelaine which is slightly more frequent.

The 1841 Census of Aberdeenshire has several additional spelling variations, which are each very rare, mostly single entries.  However they amount to a significant number in total and should all be found using Soundex searching.

To some extent Magdalen and Madeline (and their variants) can be interchangeable in some family situations. One correspondent [JP] records that her "great-grandmother was born Magdalene ... [and was] ... also known as Madeline."