A 60W GLS light bulb is a standard, commodity product. Power LEDs, by contrast, are not commodities that adhere to a single industry standard. Even if power LEDs from different vendors shared identical packaging and pinout (which few do), differences in performance would mean that one brand could not be simply interchanged with another.
There are a number of reasons why LED manufacturers?products differ considerably. Solid-state lighting is a young and developing industry, and innovations are constantly being introduced by manufacturers to improve performance characteristics and to give their products a competitive edge.
Some of the factors that result in product differentiation are:
The design, manufacture and materials used to create the LED.

Phosphor development. Different phosphors react differently to heat and to light.
LED packaging can affect how light exits the package, how much heat can be dissipated and how optics are attached.