What is one key difference between Bret Harte's Roaring Camp with that of Angel's camp described by Mark Twain?

It looks like you are asking about the difference between how the camps are described in the stories.
If we refer to the texts, Twain describes Angel's Camp as "an ancient mining camp." Meanwhile, Roaring Camp in Bret Harte's story is described as an operational camp. Essentially, the key difference between the two camps is that one of them is no longer operational or active. That would be Twain's Angel's Camp, which he calls "an ancient mining camp."
There isn't much beyond Twain's terse description of Angel's Camp in "The Celebrated Jumping Frog of Calaveras." However, Bret Harte's "The Luck of Roaring Camp" provides more details about the camp in the story.
For example, we learn that the camp settlement consists of about one hundred men. At the beginning of the story, these men congregate outside of "Cherokee Sal's" cabin. Sal is having a baby and is alone in the cabin. There are no women with her, as she is apparently the only female inhabitant at Roaring Camp. Harte tells us that Sal is a woman of ill repute and hints that she was known to the men at Roaring Camp.
According to the text, Sal dies in childbirth. The child, a baby boy, survives. The men name him Tommy Luck and adopt him as their own. They fix up Tommy Luck's cabin and even hold a christening for him. In short, the once rude, coarse characters of Roaring Camp become model citizens for Tommy's sake.
Bret Harte tells us that Tommy brings good luck to the camp.

Such was the golden summer of Roaring Camp. They were “flush times,”—and the Luck was with them. The claims had yielded enormously.

So, the key difference between Roaring Camp and Angel's Camp is that the latter is no longer operational.