It may be that there was never any distinction between canyengue and orillero as Tango styles, but that they were different ways of describing the same thing - the dance done by the immigrants and the poor who were creating Tango in the earliest period, the lower class (cangyengue) people who lived at the edge of the city (in the orillas).
(from history-of-tango.com (http://www.history-of-tango.com/canyengue.html))
Orillero-style tango is an older style of tango whose name suggests that it may have had its origins in the streets of poor outlying tenements in Buenos Aires. Later it came to refer to the man dancing around the edge of the woman. In either case, orillero-style tango was not considered acceptable in the refined salons of central Buenos Aires during the golden age of tango. To the extent that orillero-style tango is still danced it has become more like salon-style tango. It is danced with upright body posture with the dancers maintaining separate axes, and the embrace is typically offset in a V and can be either close or open.
(from tejastango.com (http://www.tejastango.com/tango_styles.html#orillero))