As long as charge oscillations do not couple to electromagnetic light these are called "surface plasmons" and if they do SP + coupled electromagnetic wave are called "surface plasmon polariton". See e.g. link.

Quite often, however, both terms are used synonymously, even if there might be situations where surface plasmons seem not to couple like e.g. in case of prism coupling where a plasmon is excited that lies completely below the light line (but certainly couples to EM waves through the metallic layer inside the prism). Also, in case of localized surface plasmons there is the electrostatic case, but then there aren't any longer charge oscillations... so even if one (sp) refers to the charge oscillations alone you usually have also the coupling to EM waves and therefore the spp case.

http://dipc.ehu.es/etxenike/admin/documentos/archivos/publicaciones/307RPP2007.pdf

Thank you

exact  and powerful answer.

Surface Plasmon Polaritons are the coupled oscillations of an electromagnetic waves with the free electrons at the metal dielectric interface. On the other hand Surface Plasmon Resonance is the phenomenon of coupling between the incident energy and the free electrons oscillation at the metal dielectric interface.

and what is the surface plasmon? @saman

Dear Mr. Motreza, here are  my answer about your question, hope you find your answer in it.

In physics, the plasmon is the quasi-particle resulting from the quantization of plasma oscillations, which are density waves of the charge carriers in a conducting medium such as a metal, semiconductor, or plasma 

Surface plasmons (or more exactly surface plasmon polaritons, SPPs) are electromagnetic excitations that propagate along the interface between a metal and a dielectric medium.

Plasmons are longitudinal excitations (strictly speaking, bulk plasmons are longitudinal waves) however surface plasmons have both longitudinal and transverse components

Surface plasmons (those plasmons confined to surfaces) interact strongly with light, resulting in a polariton They occur at the interface of a material with a positive dielectric constant with that of a negative dielectric constant

(usually a metal or doped dielectric)

there are three types of plasmons: volume plasmons,surface plasmon polaritons and localized surface plasmons

Surface plasmons are basically the quanta of plasma oscillations at a metal surface.

• When a surface plasmon couples with a photon, a quasi particle called the surface plasmon polariton (SPP) is formed.

• Volume plasmons are the excitation of the conduction electron sea that occurs in bulk metals.

• Localized surface plasmons are the excitations (nonpropagating)

of conduction electrons in metallic nanostructures coupled to the electromagnetic field.

Dear Saman,

You mentionned the following satatement:

"Plasmons are longitudinal excitations (strictly speaking, bulk plasmons are longitudinal waves) however surface plasmons have both longitudinal and transverse components"

Could you please, expalin more regarding the transversality, and/or give a reference for that?

Thank you for your time !

@saman

dear saman thank you  your attention and time that give

My main question is that:

what is the difference between ""surface plasmon"" and ""surface plasmon polariton""

it can be solve in view of K(wave vector). 

you explain the types of plasmons.

OK, I am sorry, I forgot to give you the reference, please open the attached file, thank you.