capacitor code/size?

[add4]

Hello all,

I am going through my capacitor stock, and i'm surprised at this :
I have some film caps labelled '103J100' -> this should be 10nF, 100v, right?, and some other labelled '104J100' so i'm thinking 100n,100v.
Both caps have the same package type, grey color, film box type, but the 103 caps are bigger than the 104 ones, which seems really odd to me, what am not understanding, or missing?

thanks