Your image is confusing. How does a the rifle with no magazine have the same capacity to rapid fire as the one above it? The Ar-15 appears to have more bullets immediately available, which would mean it would fire them faster.
The magazine isn't in the second picture but it has one. Looks like a Ruger 5816 to me, so if you want to see what it looks like with the magazine in it, check out their webpage. Funny enough, it looks like a 10 round mag in the AR, and the 5816 comes with a 20.
How is having a pistol grip that improves comfort and hip firing not make the weapon easier and more comfortable to use?
You're talking about personal preferences here. I tend to find them both pretty comfortable, but you really want to keep the stock at your shoulder.
How is being less visible at night not make a black gun more dangerous than one with a bright wooden sheen?
One of them is black metal, the other one is wood. Either could be painted if you wanted to I suppose, but if we're talking about night-time scenarios, using a light would make either relatively visible.
Do both guns have the same exact default trigger pull, or is the ar-15’s lighter and easier to fire?
You could probably answer these questions in less time than it took you to write them out by looking them up. The 5816 has a pull of 13.50" the base model ruger AR (8500) is 10.25" - 13.50".
These guns are different enough in actual use to make one more dangerous than the other. They both can kill you dead, but one literally is designed specifically to be deadiler in several ways. It’s one of the reasons mass murders keep using it specifically to mas murder people.