The answer to your direct question as I interpret it is 'maybe'.
The Train Engineer has two components, a transmitter and a receiver. The way your question is worded, I interpret it to ask 'Is the Train Engineer the only transmitter capable of running both track and battery power from the same transmitter unit?' Currently, in an off the shelf configuration, yes. This exists because the manufacturer of Train Engineer are the only folks to make both a unit designed to power the track in a manner like the old time power packs used in smaller scales (referred to as a trackside or base station), and an on board unit similar to a DCC unit for smaller scales mounted in the locomotive (constant track power).
There is little functional difference between a trackside and local (engine) mounted receiver. Both receive a a constant input voltage, either from your battery pack, or a clean power supply. Both control the output voltage from signals received from the transimtter (hand held). The only real funcitional difference is the trackside has a bit more 'protection' circuitry because a derailment and resulting short circuit is hard on electronics.
There are however alternatives to this system, but these may require the user to 'go an extra mile'. I am using the AirWire system in my locos, and with a bit of creativity, I am also abld to run both battery power (the original design for AirWire) and constant track power, same as the Train Engineer with an engine mounted receiver. Is it EXACTLY like Train Engineer, no, because I am not controlling the voltage to the track. That being said, one of my 'round tuits' is to build up a trackside unit from an onboard receiver and see it it can be done.
There are also other 'trackside' manufacturers. In some cases I am sure they might be able to be converted to an onboard with out much difficulty. This magazine also published a series of articles on building up your own TX/RX system.
I have deliberately evaded the DCC systems, partly because they do not relate directly to your original question, and secondly my knowledge of DCC is VERY limited, therefore I don't wish to mislead you. Greg who posted above will be able to better aid if you have questions in the DCC arena.