Not quite sure what you are asking without a bit more info,
Lightning finials come in many different shapes and lengths and materials, the 2 you have shown one looks quite short and the is long and both look to be manufactured using different materials
As UNG, not sure exactly what the question is, but the difference between simple and commercial products is mainly that commercially produced ones are designed, engineered, extensively tested and guarenteed to work.
And in the case of lightning protection to not cause any damage to the building whilst the protection system is being hit by lightning.
Additionally a simple rod or system wouldn't be accepted by a building's insurer, if lightning protection is a condition of insurance.
The first picture is an ESE and the second a regular air terminal. The ESE is expensive but only needs 2 downconductors and earths so normally quite a cost saving.
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