Difference between Dividend and Distribution.

Hi, I am thinking to add more position on AD.UN, outside of TFSA. ( currently I have small portion in TFSA).

While I was reading the report on the company, I got a little confused on the difference between Dividend and Distribution.
Especially when it comes to taxation, what would be the difference? Or is there any difference?

P.S. thank you for your hard work Dan, Mat!!