Final answer:
Fluorescence in chlorophyll molecules involves the absorption of photons and emission of light at a longer wavelength. This is distinct from resonance energy transfer, which involves non-radiative energy transfer between two closely-positioned molecules.
Step-by-step explanation:
Fluorescence in the context of chlorophyll molecules refers to a phenomenon where these molecules absorb light at certain wavelengths and then emit light at a longer wavelength. This process occurs when chlorophyll molecules in plants absorb photons and become excited to a higher energy state. Shortly after, they lose part of the absorbed energy as heat before returning to a lower energy state and emitting the excess energy as fluorescent light, which is often in the visible range but at a longer wavelength than the absorbed light.
On the other hand, the resonance energy transfer you mentioned, also known as Förster resonance energy transfer (FRET), is a different mechanism where energy is transferred non-radiatively (without the emission of a photon) between two chlorophyll molecules or between chlorophyll and another light-harvesting pigment within a close proximity. This is one of the processes involved in the light-harvesting complexes of photosynthetic organisms, which enables the transfer of energy to the reaction center where photosynthesis takes place.