What is the difference between non-inverting capacitor and a comparator?

If, by your question, you mean a non-inverting "AMPLIFIER" then not a whole lot. A comparator compares the voltage of two sources and gives a result indicating the higher of the two. An non-inverting amp, while it does some other stuff as well, can be used as a comparator. That being said, I would not install one in place of a comparator on your Bradley. The motor officer would likely not be best pleased.