In an RL circuit, voltage changes immediately upon connection to a battery, while current takes time to build up, creating a simultaneous relationship as described by Ohm's law (V=IR). The discussion highlights that in AC circuits, capacitors and inductors introduce phase shifts, with capacitors initially allowing high current and low voltage, while inductors resist changes in current. The concept of a 90-degree phase shift applies only during continuous AC supply, and the initial transient response must be calculated separately at switch-on. The conversation emphasizes that voltage and current cannot be strictly categorized as first or next without violating Kirchhoff's laws, and understanding circuits does not require a focus on electron behavior. Ultimately, both RL and RC circuits exhibit similar dynamics regarding voltage and current relationships during transients.