Jets are more aggressive and smell worse. The jets have the fully rubberized toe box, which makes them a little better for toe hooking, but the difference isn't huge.

Each shoe is better (in my opinion) for:
Jet7:
• Toe hooks
• Downturn
• Overhangs

Arrowhead:
• Comfort
• Edging
• Smell

Fundamentally, the jet 7 is a bouldering shoe. It was designed by professional boulderers specificly for very agressive overhanging climbing. The Arrowhead also excells at bouldering, but uses a much harder rubber, very good for edging. They are both quite down turned, the jet 7 is a little more agreesive then the arrowhead, but as far as fit, they are almost the same. Also, because the jet 7 is a bouldering shoe, it has features like the added rubber on the toe and heel for hooking. I own a pair of arrowheads, and suggest them to anyone looking for a high end pair of shoes. Especially to 5.10+ sport climbers. The rubber on the arrowheads will also last longer, saving the shoe from several resoles, you will have to resole the Jet 7 much more often. If you dont use these shoes in the gym, they wont need as much resoling in general, so I guess it doesnt make a huge difference.

In conclusion, both are superior quality shoes. It all comes down to what youll be using them for.