What's the difference between 'attachment before' and 'block' in views? Recently I followed a tutorial in views which listed taxonomy and gave me a short list above the view with hyperlinked first characters of taxonomy name. In this case, I created a "block". 

In investigating the default Glossary view, I see the same hyperlinked first characters of title created by using "Attachment before".

Are there advantages of using one method over the other?
Block - separate views display that can be outputted in any region of the site.
Attachment - views display that can be outputted in addition to another views display, so you can attach this display to output of another views display.

Attachment has some special options like Inherit contextual filters:Yes, Inherit exposed filters:No, so you could use one exposed filters form for both displays.