The Canon XLR is a connector type. Whether or not the circuit is balanced depends upon other things than the connector. I have seen many examples of XLR connectors used essentially for the "pro look" that do not have differential, or even balanced, circuitry behind them. An XLR connector provides the ability to provide balanced or differential signals in a single connector. An RCA solution requires two connectors for a balanced/differential circuit (one for the in-phase "+" and another for the complementary "-" signal).
The signal level is similarly dictated by the circuitry inside and not the connector itself. The most common IME is +6 dB for the differential signal since two similar drivers each provide the same level but opposite polarity, doubling the effective voltage level. However, I've seen specs all over the map, especially for consumer units. Some designs use a balanced circuit that simply terminates one side for no gain, and some may use transformers or dividers that can reduce the gain (perhaps to provide lower distortion and higher headroom for the internal signal chain).
From Wikipedia:
History and manufacturers[edit]
Male and female XLR connectors with different numbers of pins
The XLR connector (also
Cannon plug and
Cannon connector) was invented by
James H. Cannon, founder of the
Cannon Electric company, Los Angeles, California. The XLR connector originated from the
Cannon X series of connectors; by 1950, a latching mechanism was added to the connector, which produced the
Cannon XL model of connector, and by 1955, the female connector featured synthetic-rubber insulation
polychloroprene (neoprene), identified with the part-number prefix
XLR. There was also the
XLP series of connectors with hard plastic insulation, but the XLR model name is commonly used for all of the variants.
[2][3][4]
Originally, the ITT Cannon company manufactured XLR connectors in two locations: Kanagawa, Japan, and Melbourne, Australia. The Australian factory was sold to Alcatel Components in 1992 and then acquired by
Amphenol in 1998. Later, the
Switchcraft corporation manufactured compatible connectors, followed by the
Neutrik company, which made improvements to the connector, and produced a second-generation design (the X-series) that had only four parts for the cable connector, and eliminated the small screws used in the models of XLR connectors made by Cannon and Switchcraft.