What the different of this X-Rated Capacitors that have same values 105K and 400v but not have the same size.

 

Image link is broken.

 

Sorry, This is the link
http://imagebin.org/319796
Thanks in advance

 

There are compact and standard sized ones. Compact ones probably cost more but there is probably no difference in their performance.I guess it depends on the manufacturer with what size they decide to go with.

 

The smaller ones may use a dielectric with a high voltage rating so they can use a thinner film when they are made.
Or the smaller ones may be what are called metalized capacitors which use a thin deposited layer of metal on the dielectric instead of a thicker separate metal film for the conducting capacitor plate. That allows the layers to be thinner, giving a smaller cap.

 

So the they all same, but just materials.
Thank you.

 

there might be a difference in the internal inductance (parasitic inductance) of the two caps.

 

So the they all same, but just materials.
Thank you.

"X rated" made me think of the capacitors made for mains input filters, those are self healing types that don't produce a load of carbon deposit when a voltage spike ruptures the dielectric. The main objective is to avoid a sustained arc that starts a fire or blows bits of capacitor foil over everything.

Resin dipped types like some in the link can be typical of the special dielectric types used for high energy pulse applications, such as flyback tuning in CRT TVs.