JQL will give you always a list of issues - and only that. With SQL you can do more, aggregations, search for other things (Users, Projects, ...), etc.
See here for useful examples:https://confluence.atlassian.com/display/JIRA041/Example+SQL+queries+for+JIRA
Furthermore the differences mentioned by Udo, I would add one more:
SQL is standard while JQL is proprietary. It means that there are a lot of tools supporting SQL whereas JQL is restricted to JIRA.
Fortunately, there is an add-on (SQL for JIRA) which brings all the power of JQL to SQL. Therefore users can take all the benefits of SQL and JQL working together.
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
We're bringing product updates and pro tips on teamwork to ten cities around the world.Save your spot