Please clear up my confusion re: meaning of "balanced" !

There are differentially balanced equipment that the circuit is fully balanced, then there are balanced equipment that uses transformers to still get a balanced connection. There are some equipment that use XLR's but don't have a balanced connection.

Yes you can connect them. Balanced topology or not does not affect that in the least.

Here is a very simple rule that will serve you well throughout all your life, audio and otherwise: if the connectors fit, you can use them. Period.

Every single connector on every single thing made in every single country on Earth works this way. They are all designed in order to prevent damage, specifically risk of fire. Why everyone isn't told this, or hasn't figured it out, is one of the great mysteries of life.

@stuartk ,
PM or call Ralph Karsten (atmasphere).
In fact, if you search the Audiogon archives, you'll find many of his posts explaining the rational of the 'balanced topography'.
As you seem to have found, some equipment offers balanced input/outputs, but in order to achieve the AES 47 standard, the equipment must adhere to that standard. Otherwise, you might get unwanted interactions- like hum.
B

3 pin XLR connectors are considered balanced cables and connectors.

Not all devices with XLR plugs are balanced either in the input or circuitry.  That is, some amps have XLR inputs for convenience, but the (-) pin and GND pin are shorted together, so in fact you gain none of the long distance/noise cancelling benefits of a true XLR connection.

Then there are manufacturers who essentially create a new amp/preamp section for both the (+) and (-) sides.  This requires twice the parts.

I appreciate all the responses. Some went over my head. 

Thanks to millercarbon, in particular, for answering my question in a direct and non-technical manner.