A scarf is usually lighter in weight (and warmth) than a muffler, but not always. A muffler is meant to be worn in cold weather.
Both can be decorative.
http://www.google.com/search?q=scarf&es_sm=119&source=lnms&tbm=isch&sa=X&ei=NrJIVcCtAcKngwS9mYGAAg&ved=0CAcQ_AUoAQ&biw=1440&bih=712
http://www.google.com/search?q=wool+muffler&es_sm=119&biw=1440&bih=712&tbm=isch&tbo=u&source=univ&sa=X&ei=Y7JIVYtgi5Q2gbyBkA4&sqi=2&ved=0CCoQsAQ
What is the difference between 'scarf' and 'muffler'?
1 answer