May be wiser to post them with the Chinese characters, often stuff is similar in pinyin, but different in essence.
In this case, if I understand correctly the question:
世身 - shi shen in WWG.
食神 - shi shen in 4 Pillars/bazi.
First case is a line that is calculated based on self line and suggests connection with the Self, in the second case its the good old Eating God that you can find tons of resources all over the net, about.
For the first one, may be wiser to ask Harmen, he has a lot of groups, forums and stuff and sometimes responds to questions like that. There may be other sources in English that cover it, but I can't think of any right now.
And gua shen is body of the hexagram, lots of info on that all over the places.