What are the main differences between local and global indexes in Apache Phoenix?

When is it good to use one and when the other?
I tried googling but I don't find anything on that topic.

Also, I know how to list all indexes but is there a way to tell which ones are global and which ones local?

My guess is this:

When I run this SQL query local indexes will give me cnt=2 while global will give me cnt=1.

select table_name , count (*) as cnt  
from  
system.catalog  where  table_type = 'i'    
group by  TABLE_NAME 
order by count(*) desc;  

Is that a good criterion to distinguish between local and global indexes?