What's the difference between both the tips? I know one is copper while the other isn't. What is the benefit of one over the other and has anyone purchased the copper bit before? What's your experience?
Solder dissolves copper to a small extent.
You'll never notice the small amount of copper that is dissolved from wires or PCB traces when you make a joint, but a bare copper soldering iron tip loses enough over time that you'll notice it fairly quickly.
For this reason, good soldering iron tips have a copper core (to transport the heat better) and a special alloy plating that doesn't dissolve in copper.
The silvery tips in the first photo are plated to protect the copper core. Depending on the quality of the plating, they should last a fairly long time before they begin to develop pits or cracks.
The bare copper tips in the second photo are not plated. They will oxidize (turn black) almost immediately along the length of the tip, and the tip itself will begin showing pits and roughness after just a little bit of use. (Hours to minutes depending on temperature and the specific solder alloy used - lead free being worse than solder with lead.)
You'll want to use plated tips from a good manufacturer. They cost more up front, but they last so much longer that the difference is worth it.
The bare copper tips in the question are not some intermediate stage during the manufacturing. They are a finished product that you can buy on AliExpress, Banggood and other places that sell cheap junk.
My first guess was that the bare copper tips could be intended for wood burning (drawing on wood with heat,) but the advertisements on Aliexpress are quite explicit that the bare copper tips are intended for electronics work.
I wouldn't buy them.
You'll have to periodically (every few hours) reshape and tin them.
I used to have to do that all the time with the cheap soldering irons I used as a kid (late 1970s to the end of the 1980s.) I made my own tips because it was cheaper than buying the correct ones for my cheap iron - and the purchased tips didn't last any longer than my hand made, pure copper tips.
Those appear to be Hakko compatible tips. Find a supplier with a good name that sells proper Hakko tips for your Hakko (or compatible) iron.
Solder (tin specifically) dissolves copper. Some more than others. I've even had plated chisel tip turn into a 6mm radius hemispherical groove after 2 weeks of soldering wire with lead-free which dissolves particularly badly. Good tips have thin iron plating under the wetted area to prevent this and without chrome plating elsewhere the solder can wet the entire tip uncontrolled...not that you want exposed hot copper but it can be a pain to control.