Best practices for what to include in trello vs issues

[Trading]

We are just beginning to use the bit bucket cloud repository. I am not exactly sure what is the use of trello versus the issues. If I create an enhancement feature in issues and assign it to a developer , then what is the use of creating a task in trello for the developer.

Also, assuming that I create a task in trello to track an issue, can I have some way where I can at least put the permit information for that issue in that trello task? Right now, the only way I know is to put the entire URL of the commit. That just makes it ugly and difficult to read. It would be better if commit number and trello can automatically put a link to the appropriate commit.

Put in another way, are there any integrations between the issue tracker and trello on the bit bucket cloud?

Also, assuming that we have a number of tasks in trello, is there a way to search using a keyword specifically in trello. Otherwise it is not of much use if we cannot have a history.

Thank you for any inputs