Specially means "for a special purpose." If you walk into a room that's been specially decorated for St. Patrick's Day, there is probably a lot of green involved, and a shamrock or two.
Use the adverb specially as a slightly less formal version of especially to mean something done in a particular way — like the fabric of a raincoat that's been specially treated to repel water. Specially also tells about something done for a special occasion, like when you make your sister a specially decorated cake for her birthday.