Gents, it pretty much is as simple as that.
INPA comes with EDIABAS, which is almost like a client server application, it is this that does the actual comms with the car, and translates the data into INPA, which is just a front end.
INPA is genuine BMW, INPA however was only meant for internal factory use, so its not as "pretty" as DIS, but it works very well, and the information that you get out of it is brilliant, you can also interact with the car.
Example. I suspect that my EGR flap is not working, you can turn it on and off, or I want to activate my aircon flaps cause i suspect one is not working, you can do so.
INPA IS QUICK!!!! An instruction on DIS can take a few minutes to run, but INPA is more or less instant, its fantastic.
There are some issues though, because its "factory software", its not as refined, and often throws out errors, and there is a large list of incompatability between modules, meaning that you will have hours of "fun" trying to get it to do what you want too. I still cannot diagnose my M60 on INPA, the DME 3.3 is listed but it just does not work.
Great for error codes though, and not just error no 12345, it actually gives you a decent description.
It cannot do any coding, for that, there is a tool NCS Expert, but this one is seriously not for the faint hearted, this turns fine BMW's into rather large paperweights if you dont know what your doing.