Afoxé (ah-fo-SHEH) is basically candomblé with the religion taken out...the use of candomblé rhythms and "songs" in social, non-religious settings like Carnival and weekly dances. The principal rhythm associated with afoxé is ijexá (ee-zheh-SHAH), a more subtle and complicated version of what you might hear pounded out on the Maxwell House coffee can for a late-hours Manhattan cocktail party conga line (a modified version was also used in composer Stan Worth's theme for the 1960s George of the Jungle cartoon series). On terreiros de candomblé ijexá is associated with Oxalá (the father) and Oxum (goddess of sweet waters).
Embaixada Africana (African Embassy) was the first afoxé, parading in the Carnival of 1895. The next year afoxé Pândego da África (African Hijinks) went out, and in 1905 an afoxé climbed the Ladeira da Barroquinha to parade up the Ladeira de São Bento, thereby breaking a tacit understanding that the Carnival groups from the lower (and darker) economic classes had their areas (Baixa dos Sapateiros, Barroquinha, Pelourinho) and the upper classes had theirs (Avenida Sete de Setembro, Piedade). Salvador's largest and most widely known afoxé -- Filhos de Gandhy -- was formed in 1949 by a stevedore whose inspiration was the great Indian leader and pacifist (who had been assassinated the year before). Other afoxés include Filhos de Korin Efan, Badauê, and Filhas de Oxum. From 1904 until 1918 afoxés were forbidden to march during Carnival, ostensibly to combat "crime, ao deboche, e à desordem (crime, debauchery, and disorder)".
Blocos Afros are Carnival blocos (groups) which, put simply, celebrate cultural manifestations of African origin. The rhythms are usually based in what is called "samba reggae" (which comes in a number of variations) and the dress is African-inspired (in contrast to afoxé Filhos de Gandhy, whose robes draw their inspiration from the Indian subcontinent). Olodum, Ilê Aiyê, and Ara Ketu are the three biggest and best-known blocos afros...Ara Ketu -- and in international terms Olodum to an even greater degree -- having achieved significant commercial success. Other blocos afros include Muzenza (from Liberdade), and Malê de Balê (of Itapoan), who drew the inspiration for their name from the Malê Revolt.
Muzenza, left, is from the neighborhood of Liberdade; Ilê Aiyé, right, is also from Liberdade, from an area called "Curuzu"
With respect to the name "Olodum", the best known of Salvador's blocos afros (both Michael Jackson and Paul Simon have recorded with them), I've heard respectful stories in several variations but with the common theme of reaching deep into tradition and pietous religosity for inspiration...
Principal founder Geraldo Miranda (popularly called Geraldão -- Big Gerald), who went on to found Muzenza after an internal breach, tells it like this, however (my translation):
"As for the name of the bloco, Olodum, I was the one who came up with it, thanks to a friend, a filha-de-santo (candomblé adept), who happened to mention that Olo and Dum were two gods, without mentioning anything about their origins or if there was really any religious basis for this. I stuck the two names together and nobody disagreed and so it was, Olodum."
Geraldão was correct in his unvoiced but implied suspicion that there wasn't any true religious basis for this, although it wasn't completely off the mark.
I mention this not only to puncture a glossed image which is often presented to the world (not only by some of these groups; isn't this pretty much universal human behavior?), but as intro to the fact(s) that in spite of some groups' in-some-cases questionable origins, the rhythms and music they play can nevertheless be wonderful (gee! sounds like Christianity!).
Olodum played New York's Summerfest in...what, 1990? I wrote the descriptive part of the grant request to the New York State Council for the Arts, bullshitting as I hadn't actually ever heard Olodum. But they came through with the bucks and Olodum played Central Park.
Wonderful people have come out of Olodum, but this bloco ain't my bag.