These experiences are meant as a framework to who you are as a person and where the conversation will go (although a minority of interviewers will choose not to look at them at all). I don't know what you have chosen to write about, but definitely include hobbies and other things that are important to you. I put down some family-related stuff, which my interviewer really wanted to talk about.
To answer your question, I repeated myself given that one of my significant activities was the best example about how I serve others. But I used different words obviously. Because you have more words to use, I treated the "demonstrated service to others" as a secondary-like question where I could use an anecdote whereas the 100-word limit was essentially a brief description of the activity and what I learned.