Upon being disappointed about aircraft engines vs. tank engines:
As mentioned before, both are gas turbines. A gas turbine is a brayton cycle internal combustion engine with a large compressor for air intake. What you use it for doesn't matter so much for the purposes of calling it a gas turbine.
The interesting thing about these babies is that you can almost freely decide how you want the power output to happen. You can build a gas turbine that outputs just about all its power through a jet exhaust, reserving only just enough for shaft power to drive its own compressor. If you do that, you get a jet engine. However, you can also take a nearly identical gas turbine and build it so that it outputs almost all its power as shaft power, reserving only just enough "thrust" to push the exhaust out of the combustion chamber. You can then stick something on that rotating shaft, like a propeller. Suddenly, the same kind of engine powers both a propeller airplane (turboprop) and a jet airplane (turbojet), and even a hybrid between the two (turbofan). Is your mind blown yet?
And of course, instead of a propeller you can also stick an electricity generator on there, to create power for your city - or for a tank's electric motors.
Gas turbines are extremely awesome, useful and multipurpose devices and you should totally read up on all the things they can do. Heck, someone wants to build a millimeter sized one for on-person power production to recharge your phone on the go and stuff...