diff between capacitor & a rf capacitor

Different types (construction and dielectric materials) of capacitor have different charcteristics, eg act differently at different frequencies, respond differently to current spikes etc.
An aluminium electrolytic is great for storing charge in a power supply, but at high frequeny is more like a resistor.
RF capaciors tend to me much smaller values and physical size and are of materials and construction specifically suited to high frequencies. EG polythene or ceramic dielectric.
If you google capacitor dielectrics, characteristics, types or somesuch you will probably get a fuller explanation.
Del