A very nice one is the pulse width (e.g. 1 ps vs 20 fs) and the energy of the photons of the laser pulse.

With very short laser pulses, we need the Heisenberg uncertainty principle to explain that the delta lambda becomes larger (around fundamental of e.g. 800 nm).

This is "tangible" for first year students. To make Heisenberg uncertainty more approachable.

This is a very interesting question and it highlights the fact that we don't have a fully unified description of physical phenomena. I have been working on a fully unified approach called the spacetime wave theory:

Preprint The Space Time Wave Theory (August 2021)

Data Prerecording of Conference Presentation on the Unification of Physics

In this approach there is no distinction between classical and quantum. In this approach light is quantised because that is the way it is emitted. Quantisation is not an inherent property of light, just a result of the fact that atomic bound electrons can only occupy discrete energy states. The reason for the quantisation of electrons is due to the nature of the electron as a looped wave in spacetime which encircles the nucleus many times and adopts energy states which have a local minimum. The cause of the property electric charge is explained by the Spacetime Wave Theory.

With this approach you can take a phenomenon such as the photoelectric effect and treat the incoming photon as a wave quantum with a certain energy which may or may not be sufficient to be absorbed by the orbital electron (which is a looped wave in spacetime) to move it to a higher energy state which removes it from the atom.

So by adopting a new physical description, we get rid of the false distinction between quantum and classical.

Richard