I am wondering if other planets in our solar system have such a big variety of elements as our Earth does. And if not why is Earth different?

The distribution of elements varies a bit throughout the solar system, because of the different conditions where the planets were formed. But the Earth isn't particularly unusual.

 

 

The bulk composition of the Earth by elemental-mass is roughly similar to the gross composition of the solar system, with the major differences being that Earth is missing a great deal of the volatile elements hydrogen, helium, neon, and nitrogen, as well as carbon which has been lost as volatile hydrocarbons. The remaining elemental composition is roughly typical of the "rocky" inner planets, which formed in the thermal zone where solar heat drove volatile compounds into space. The Earth retains oxygen as the second-largest component of its mass (and largest atomic-fraction), mainly from this element being retained in silicate minerals which have a very high melting point and low vapor pressure.

https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements

Thank you Strange.

 

This also helps me understand your comment in my other post about Heavy elements.