What makes names of weed different from each other?

I guess it's just a way to categorize strains and it's a way for us to keep track of genetics and know what's what.

 

 
 
 It's better than just numbering them, don't you think? If you've ever been strain shopping, you'll see that there's a TON of variety. Some are named for the breeders who bred them, some are named for their traits, others are named for the parent plants, and others still, are named for the locations where they originated from.
 
 
  As for the plants you've mentioned, they are two completely different strains, Bubba Kush is specifically a cross between Bubble Gum and Kush, while OG Kush's heritage is a little more 'mysterious', although the current plant most in circulation is thought to be Chemdawg and a Thai-Kush male cross (there was another, older, 'OG Kush', which was just a homemade Kush cross that folks from Overgrow used to trade around during the years just before they closed... the plants were rumored to be one in the same, but it's more likely a coincidence that they were both called this during roughly the same years. This is why it's beneficial to have different strain names; those two, entirely different plants, have been mixed up and confused for years... many people don't even believe in the latter plant, because they weren't using the OG forums at the time and can't recall all the trading going on!  )
 
 
  All those different names, and plants, ALL carry different and unique phytochemical properties, they produce different cannabinoid ratios, and have very different terpenes contents, and flavor profiles. Even plants within an individual strain, and especially from a new cross between different parent strains can be different, these are known as phenotypes, or phenos... there is much more to it than being indica or sativa!
 
 
 A stable cross, with similar parent types or phenos being bred with over time, will display fewer phenotypes or even just one phenotype and much less variety, or in other words it will produce more stable offspring, which is a good thing when you've found 'the plant'. But a newer cross between two entirely different strains, will produce offspring carrying and displaying traits in an array between the mother, and father.
 
 
 
 Hope this helps clear things up!

 

Kush from the Kush mountain range is where the original gene pool that serves as parentage to all various cultivars of Indica originated from.  So, folks who call their weed Kush have morphed it into an "catch all" phrase for any pot that basically gets you stoned pretyy quick onset and  potent. 
 
Other exotic names that are used are mostly contrived for advertising/marketing purposes--and can be essentially sorted as "lows" "mids" "headies".

 

Wow, I actually learned something from GC. Thank you!!

 

I went to the dispensary yesterday and bought something they recommended to knock me out at night called Hindu Shark. Has anyone ever heard of that? It was at the high end of their prices, considered top shelf. I 've never heard of it.
 
Seems to be pretty good weed though. Tastes perfume-y

 

Never heard of it, but may have smoked it.
BadKittySmiles is obviously 100% correct... But do remember that these names are given by a bunch of stoners.
 
Some of these "stoners" are intelligent and profession...
Some throw out names for marketing, will make up a name for what ever needs one (even if it already has one). Think Ted, from pineapple express. 
 
So names are nowhere near standardized enough. Some strains that are more famous are well known and distinct enough that you can't get away calling some random herb the same thing... But there is no regulation or testing, so you need to be aware and watch out for yourself.