hey, afterwards usually indicates "immediately following" and later is following the item or event but no particular time frame. "We went to see a movie, afterwards, we got a snack." "Later we went to her house." Soon and Shortly, in that context is the same. Shortly is more slang-ish.

"Later" may not have an event involved. Afterward and After imply an event. "I will see you later.." After often is placed before the activity "After brushing my heath we will eat." Afterward is often alone - taking the place of the activity. "I would like to visit afterward and catch up." After what? We would need the context. Soon afterwards, we will get ice-cream. We went there soon afterwards. Shortly afterwards we will get ice-cream. We went there shortly afterwards. They check out as the same thing with me.