Lets say there is not much. As for the spiderman sig, it needs text, better lighting and some erase of the deaspace. MAybe even a colored version would work better. Sorry but it just looks like you did nearly nothing. The same goes for the second one, work on your text.
first has a lil bit of FHS going on (floating head syndrome) but overall its not bad 2nd well it just needs some more effects imo