The transformer used in normal converter and resonant converter will be different, because in resonant converter higher frequency is used so the core will be different. For example a 3C8 ferrite core can be used up to a maximum of 200KHz switching frequency, whereas in resonant converter higher than this frequency is used say 1MHz so a 3F1 ferrite core (for example) is used. And so on.
For the wire, higher the frequency, more will be the skin effect. So a multiple strands of wire will be used. Say for example #22 SWG wire has a current of 1A, but in SMPS, three or four wire of #28 SWG will give a good result (#28 wire withstand of 0.25A).