Ah resin casting is like a type of mold casting. To be specific, the act of mold casting is taken as pouring a molten liquid into a shape that mimics desired product. hence, when you say 'resin casting', you mean to make molds using resins. I hope that makes some sense!
Always exercise proper care while doing the casting using resins. This stuff is potentially lethal and fumes may be poisonous or harmful, since they may get into the body and act as carcinogens. Be very careful while dealing with them. Use this guide:http://www.resinobsession.com/Resin-Resin-Resin/120/Safety-tips-for-working-with-resin.html