We know many explorers at the time weren't too happy with Cameron's imprudent 1995 dives where his Russian crew damaged the wreck, but I don't think Ballard ever spoke about his position on the matter (please correct me if I'm wrong).
Since they teamed up in 2012 for National Geographic's "Titanic: 20 years later with James Cameron" and have both recently backed a bid by a group of British museums to acquire artifacts, I'd say that they seem to get along just fine.
Well they both have taken a lot of critisism over the years for how they handled their Titanic expeditions but I've never read or heard them bad mouthing each other. I know that Cameron has a reputation in the movie industry as being a dictator with no tators. But thats probably just his style. Without Ballard and Camerons work a lot of what we know today wouldn't have been discovered. I will cut them slack on whatever mistakes they might have made over the years because if they didn't do what they did and Titanic was found a lot later we wouldn't have the info we do. Soon she will be in a state where they won't be able to go inside anymore. Just my opinion of course.
I whole-heartily agree. If JC hadn't went inside, I doubt we would have as much footage as we do today. I heard they even found the Firemen's Spiral Staircase. If Bob Ballard hadn't found her..oof. Imagine if we found her in the 2019 condition! Basically, they worked together in the past, without even knowing. You know what I mean?