TuneECU and Power Commander V (PCV) are both tuning tools used to optimize the performance of your motorcycle's engine, but they work in different ways and have different capabilities.
TuneECU: This is an application that allows you to reprogram, diagnose and test the Engine Control Unit (ECU) of motorcycles. It is used to adjust fueling, ignition timing, and other parameters directly in the factory ECU. It essentially replaces the stock firmware on your ECU with custom firmware. The major advantage is that it allows a full remap of the fueling, ignition and other important settings directly on the ECU. However, the downsides are that it can be more complex and riskier than using a PCV because you're directly changing the ECU's settings. There's also the potential for warranty issues if your bike is still under warranty, as changes are permanent and detectable.
Power Commander V: The PCV is an external module that intercepts the signals going to the injectors from the ECU, modifies these signals based on the map loaded into the PCV, and then sends the modified signal to the injectors. This approach doesn't change anything in the factory ECU, meaning it's not detectable and doesn't risk voiding your warranty. The PCV also has a greater range of adjustability, being able to adjust fuel delivery at any RPM, and can accommodate additional modules for further tuning options like quick shifters, ignition control, etc. The main downside is the added cost and complexity of installing an additional piece of hardware, and it only alters fueling, not other parameters like ignition timing unless additional modules are purchased.
In summary, TuneECU alters the motorcycle's ECU directly and comprehensively, whereas Power Commander V intercepts and modifies signals without altering the factory ECU. Which one is best for you will depend on your specific needs, your level of technical expertise, and the specifics of your bike and its ECU.