I am a gigantic Halo fan... that is why I am disappointed with Destiny.
If you're a gigantic halo fan I refuse to believe that you actually think no one would notice if suddenly a bunch of Vox, Devil Worshipping Fallen, and Hive creatures popped into a Halo encounter..... That just doesn't make any sense,
Sure there are similarities in art style and themes, just like between Halo and Marathon. Doesn't mean they aren't totally different games.
Factions, number of weapons, weapon customization, focus trees, personalized transports, hub worlds, classes, space magic, armor with stats, loot systems, public events, raids, storyline, lore, weapon design, etc etc etc are all wildly different than Halo.
Sure, some of the armors, ships, and Skyboxes remind one of halo, maybe even Ghost somehow reminds you of Cortana.
That said, there are no rugged space marines, no 7.62 assault rifles and spartan lasers, no warthog like vehicles running around, no iconic hero, no galaxy spanning traversal, no alien covenant under a religious banner, no flood like bio weapon, no huge reliance on grenades, no ship to ship space navy battles, no intimate relationship between yourself and a companion character, etc etc etc.
Destiny is pretty far removed from Halo if you're a Halo fan.
Someone never playing either and seeing more similarities is somewhat forgivable.