Most track rings are higher quality as far as roundness. Road rings are typically lighter. BMX stuff is heavier (NOT ALWAYS) but often there's less worry about true roundness.
Not everything is set in stone. there are exceptions but these are the "rules" of thumb.
Best rings are Sugino in my experience.
That is one of the dumbest things I have read on here in a long time! lol Where did you come up with this silly statement? Why would track rings be any more or less round than a road or BMX ring? Do you think that a Dura Ace or Campy Record ring is really not round? lol
Now to answer the question.
A track ring and BMX ring basically have straight teeth and road rings have different ramps other devices to allow for smoother and better shifting. Road rings are also thinner because their chains are thinner to allow for the chains to work on more cogs on the cassette as it goes from 7 to 8 to 9 to 10 and eventually 11 cogs on the rear wheel. Track and BMW use 2 size chains for one of two thickness rings/cogs.
As for weight, it all depends on which one you go with.
The Sugino comment above by stewardmike03 would have to be solely a FG/SS comment as most would prefer a Shimano or Campy ring over a Sugino on a Road Bike!
As someone who has a long history with BMX bikes before recently making the leap to fixed gear (my back couldn't take it!)...I raced semi-pro some years back and continue to be somewhat of an old-school BMX enthusiast...I can assure you that the the statement of track rings being "more round" couldn't be more false. It's a sh*tty component maker that creates bad chainrings...BMX, track or otherwise.
The biggest difference is that BMX chainrings usually have 110 bolt spacing, meaning more chainring/less crank arm spider than "track" cranks/rings when you move into 40+ teeth territory.
i suppose, what he means, is that what's the difference in perforumance from 144, 130, and 110 bcd, if the tooth count is the same. To me that's more of an intelligent newb question, cause the first thing i thought when i saw this was "why are there all these different standard?"
the only think i can come up with for WHY is that manufactures come out with their own standards, and with most things, they got adopted by others.
as for the roundness statement, cheap alloys don't always hold their shape.
Agreed...that is an intelligent question. Speaking only for myself, I've run track cranks/chainrings as well as BMX-style stuff on my fixed gear (currently running 170mm Bulletproofs w/110 bcd) and have never noticed a difference in performance. As far as aesthetics go, I prefer 110 bcd w/ smaller spider.
LOL...Nice. What I meant and implied was that TRACK chainrings (1/8" and 144bcd for the most part) are nearly ALL high quality. Only a few no-name manufacturers exist that make shoddy TRACK chainrings. Road rings do indeed have ramping and pinning but there are some phenominal 130bcd rings...TA Specialties for example...that are made singlespeed or track use...these have straight cut teeth. And last BMX...again there are some excellent examples but just as many crappy knock-off pieces...and yes most are 110bcd. When it comes to stiffness, roundness, and durability you will find it increasingly difficult to beat a true TRACK chainring...Sugino 75's will outlast nearly any other.