If we are to compare these two games, I think it just can't be done, not with any sort of justice to either one anyways.
- Defiance
MMORPG - designed for lots of players in the same instance to complete public styled events, instanced co-op and pvp matches.
Game play - third person view, great shooting mechanic, upgrade ability through mods for guns, Ego device with abilities to change your class on the fly.
- Destiny
FPSRPG with continuous drop in drop out match making connection - designed for 12 -16 players (roughly) in the same instance for public events, instanced 3 man fire teams, pvp matches up to 12 - 16 players. Strikes and Raids (Not sure how raids will work but believe to be 6 player).
Game play - Solid shooting mechanic, upgrade ability through gun upgrades after reaching xp and usage amounts for the gun. Class tree upgrades well dynamically change the game, i.e. hunter class opens up knife throwing. Must start a new character if you wish to try a different class.
BETA.
From then on things go pretty opinionated, pvp on both seem bad, but Bungie at least is willing to make changes and get things sorted. I found that the social aspect on Destiny is lacking, might be designed to be played with friends instead of random players though where as Defiance has a text chat (that sorta works after a year of bugging them about it).
Graphics wise and sound I will give it to Destiny, with Defiance you get same type of music playing which seems to be dubstep type. Destiny looks fantastic on the newer consoles, but even on the old gen it still looks better than defiance (I did say it was going to be opinionated) The Xbox 360 system seems to have some performance issues when it comes to Destiny but when on the Xbox one they were non existent. When the game launches we might see some improvement with that.
Loved the thrill of the chase for loot, in Defiance you got loot but seems to always give you birdshot pump shotty or other crappy guns you never were wanting. They decided to put in scaling of enemies and make grenades a consumable. Destiny on the other hand has rechargeable grenades like Defiance used to have, their enemies are scaled from the get go and loot drops are much better since Destiny deals with both weapons and armor drops. Better armor means better stats for your character and possible bonuses to your guns/grenades/ammo. With Defiance and the "Longer more fulling chase" it just drains the life out of me.
Destiny will have way more areas to explore once it is released on September 9th, Defiance only has 2 areas with a third coming "soon". Lots of tunnels and underground places to find and go spelunking in Destiny, but could only get so far due to high leveled enemies who shall not let me pass. Defiance, most things are on the surface and thats about what you see is what you get. Also Destiny is going to track stats with their website and a mobile phone companion app. Defiance had a website for something to do with your character but I think that was taken down some time ago.
The Tower, a social hub area for Destiny to shop for gear, go to your bank, grab and turn in bounties and see if you have new messages at the post master. Defiance has, the crater? A bar that sits there and has no interaction with the users. Lastly Defiance has been out for over a year now and they are still working on the netcode/connection problems along with numerous bugs and glitches. Destiny had significantly better connection handling and with their recent testing should only get better.
Last but not least, dev teams. Bungie has 400+ people working on Destiny, estimates of something along 500 million dollar budget for the franchise. Defiance had a team but was laid off and then moved to a new location with a smaller team and it just went down hill from there. Currently we got a couple of new faces that seem to be helping out and making changes, but only towards one dream, one vision.
I liked playing defiance, I got my monies worth out of it, but when Destiny is out I will probably be playing that for a very long time. These are my thoughts and opinions on Destiny vs Defiance.

