Differences between Dimmable and Non-Dimmable LED Lights

[Stonent]

I found a fairly decent looking non-dimmable bulb at Walmart for $2.17 each (60W Replacement bulb) and it is quite bright (almost think it could replace a 75W bulb)

However they had dimmable ones that looked exactly the same but were nearly twice as expensive.

I was wondering what internal differences there were between dimmable and non-dimmable LED light bulbs?

[Belgarion]

Digikey has an article describing dimming, which also mentions that LED lamps might not dim properly using a standard triac dimmer.
http://www.digikey.com/en/articles/techzone/2011/jul/dimming-leds-with-traditional-triac-dimmers

Basically the triac dimmer chops the AC sine curve and if the LED circuit is not made to handle that it will behave oddly.

[coppice]

Try using a traditional dimmer with a LED lamp using a RC supply and wait for the flames to appear. A triac dimmer causes massive harmonic content, and at those frequencies the impedance of the capacitor in the RC supply can be rather low.

[Seekonk]

Your results may vary.  I have a A19 LED lamp I dim for my dog to get down stairs  with only a .05uf capacitor in series.  With another one, that makes the LED flash.  I think most of them will dim somewhat with standard dimmer if a .47uf / 100 ohm RC network is parallel with LED lamp.