I´ll try a quick answer. Radioluminescence is caused by irradiation of certain materials with radioactive particles and photons. This radioluminescence can be prompt, called fluorescence, or delayed, called phosphorescence. Distinctions are the processes in the solid. Primarily no statement to delay.

Scintillation is the prompt emission of "visible" light of irradiated substances, the scintillators. So if you want, scintillations are a subgroup of radioluminescence.

I´ll try a quick answer. Radioluminescence is caused by irradiation of certain materials with radioactive particles and photons. This radioluminescence can be prompt, called fluorescence, or delayed, called phosphorescence. Distinctions are the processes in the solid. Primarily no statement to delay.

Scintillation is the prompt emission of "visible" light of irradiated substances, the scintillators. So if you want, scintillations are a subgroup of radioluminescence.

The two processes are similar but not identical. Heavy hitters will offer more details but before they weigh in, I can offer a brief summary the way I see it. In radioluminescence, the ionising radiation produces free electrons which recombine at a luminescence centre to produce luminescence. In scintillation, the ionised atom itself relaxes via a series of excited levels to produce luminescence. The atom or molecule in the latter is excited by collision with the radiation particle (beta, gamma etc) by collision. One might ask, where does the electron produced in the ionising process in scintillation go? Well, unlike in RL where the excess energy is lost as luminescence, in the scintillation process, the electron loses energy by inelastic scattering. These are my thoughts but as I said, heavyweights might show up later and offer more punch.

Good contributions.  The important distinction is that the luminescence is not emitted from the same luminescence center.  Scintillation follows relation of the atom itself via excited states whereas radioluminescence is due to emission at a recombination centre.  The two processes, although technically fluorescence, are not identical.  In this case, perhaps we cannot make comparisons in terms of lifetimes because this will have different definitions in the two instances.

I´ve some problems to allocate scintillations to single atoms. Its true, scintillation in gases are the consequence of excitation of single atoms or molecules by the ionisating radiation. But in solid states or plastic materials, the scintillation occurs from the effects of the solid state conditions (traps, activator centres, ...). And the deexcitation must not happen at the location of the prior excitation because of diffusion processes of electrons in the conduction band. In both cases scintillations are a prompt process (prompt when neglecting in solids the diffusion times and the usual deexcitation times of the excitated states). Could you please help me dear Makaiko to deepen my knowledge?

Hanno, sorry for the delay in replying.  I have now seen your post and will reply in due course.

Radioluminescence is usually defined from the excitors, i.e alfa (helium nuclei), beta (electrons) and gamma (E-M radiation > UV. Sometimes including UV). Not to mention neutrons and other particles. It could be either fluorescence or phosphorescence (including so called delayed fluorescence).

Scintillation is simply the emitting light process following the energy departation of the excitors above.  It does not have to be prompt eventhough it is often desirable. It is sort of implied that you focus on the prompt mechanisms when dealing with a "scintillator". But several so called scintillators inhibit long afterglow properties. "Scintillator" used to denote a single crystal material but since the introduction of ceramic scintillators, essentially based on powder phosphors, this distinction has been abandoned. Also, polycrystalline phosphors such as intensifying screens have been noted to be called "scintillator" in the scientific litterature. However, I have never seen a single crystal scintillator be called "phosphor" (yet).

I´d say the denotations are in practice quite equal but I lean towards Hanno Kriegers distinction above without condemning you if you don´t. 

Hanno, my definition covers solids too.  This is implicit in the loss of electron energy due to inelastic scattering.  Jan has described this very well too.  Maybe now the question is settled.

Thanks to all the experts for giving your replies. 

Upon excitation with Radioactively created energy regardless of its nature [electrons,positrons,x-rays, gamma rays, neutrons or charged particles] that is incident on say a solid, there is immediate emission of light that may be termed radioluminescense.

The light emission that occurs at a particular wavelength, reaches a peak of emission and decays to 1/e value of its peak intensity in 5 microseconds or less is arbritarily termed a scintillation light and the solid a "Scintillator", the rest are designated as "Phosphosr" with long decay of light after the exciting source has been removed. Yes, scintillators are also found in liquids, ergo Liquid Scintillators, or gases and even plastic. You have, hence, Inorganic Scintillators both crystalline, polycrystalline, amorphous, and Organic Scintillators [The PVT base activated with p-terphynyl, being an example] and Liquid and Gaseous Scintillators whose chief characteristics is that the emitted light is gone within 5 microseconds. I  have deliberately not addressed the mechanism phenomena that is attributed to what causes scintillation [relatively short emission of luminescence upon excitation] as this a debatable subject that is not yet settled fully with 100% consensus. Even the most well known scintillator, NaI(Tl), the workhorse scintillator of the industry, there are scientists who will debate the mechanism---Google it.

Radioluminescence is generally of single photon emissions whereas scintillation is a 'burst' of photons. Radioluminescence may be temperature dependent whereas scintillation is not.

Encyclopædia Britannica defines radioluminescence as the phenomenon where "... an appropriate material is excited to luminescence by a radioactive substance".  However, the term is also sometimes used to describe emission of light from other sources of ionizing radiation.

Scintillation implies that the emission of light in response to radiation is fast, as opposed to phosphorescence.

The use of either terminology does not imply a difference in the physical process driving the emission of light.