What's the difference between medieval shop signs and modern ones? Are there any links?

The spelling? Visual with pictures and shapes and other graphics, since people couldn't read. See also Stained Glass Windows in churches. Google Images of medieval shop signs -- https://www.google.com/search?q=medieval+shop+signs&hl=en&client=firefox&hs=hZB&tbo=d&rls=org.mozilla:en-US:official&source=lnms&tbm=isch&sa=X&ei=kjMhUYySG8HXyAGt9YHoAQ&ved=0CAoQ_AUoAQ&biw=1024&bih=570

What do you want? What is the assignment?

As I understand it, there were usually guild logos on shops signs. Each guild had their own picture. Many people couldn't read.

Thanks I have done it now

So what did you come up with?