What is the difference between a resonant and a non-resonant circuit?

When a circuit is said to be resonate it means a signal or wave that is being generated has some relationship with a reflected or feedback signal such that the generated signal is reinforced with the reflected or feedback signal. This reinforcing of the signal may cause a standing wave of constructive interference and required the generation of the signal and the reflection or feed back to be in phase or Coherent. if there is no phase coherency then it can be harder to achieve the standing wave of constructive interference. However is the Phase is detected and delay is compensated it can be achieved like in a laser ring gyro, which uses two resonate cavities that have there path length adapted to cope with heat expiation.