They may look the same but they're not...

 

CFLs (Compact Fluorescent Lamps]

Performance in both lamp life and light is dependent on the electronic ballasting in the base of the lamp.  Manufacturers vary In circuitry design.  The number of electronic components can range from 16 to a high of 36.  Performance and price are affected not only by the ballast design, but also the quality and tolerances of the individual parts themselves.  These parts are rated in plus or minus tolerance. A component with a +/- 5% will operate better than the less expensive component that is rated at +/- 10%.

Heat is a prime concern 

These Components have limits. All CFL ballasts have electrolytic capacitors.  The electrolytic capacitor contains a liquid that can be depleted and cause premature failure if the operating temperature is exceeded.  The better quality CFLs have designed product to be operated in commercial applications in any burning position.  This ability to tolerate higher heat from longer burning hours gives these CFLs a longer life expectancy and maintained light output.  

Why do capacitors fail?  

Electrolytic capacitors use a semi-liquid electrolyte inside the case to make electrical contact with the foil windings.  This electrical interface is inherent in the capacitor's ability to carry current and function as an energy storage unit for the electrical power input.  When the interface between the electrolyte and the metallic foil windings begins to degrade, the electrical connection begins to fail.  Heat build—up is the primary cause of this degradation, which, depending on severity, can cause either short-term catastrophic failure, or long term functional degradation.  Similar to the life expectancy of a silicon semiconductor die, the life expectancy or an electrolytic capacitor relates directly to it's internal temperature.  Every 10 degree  increase in internal temperature halves the component Lifetime.