TrxR,
Yours are very basic questions, and best answered by going to the bullet makers web sites.
Many are the ways to make these bullets.
Most like Berger and Barnes, Nosler, Sierra, Hornady,,
, go through great length to explain how their bullets are made and you'll find on each site that each makers bullet is indeed made better than the competitors bullet.
In short, there are "cup-n-core" bullets, an alloyed copper jacket with a lead composite core,
There are "bonded bullets" where a jacket is fused to the core
There are,,,,etc,,,,,
Full copper alloy bullets preform quite well whne the loader takes care to make them preform.
The parent site "Accurate Shooter.com" has many articals about various bullets,
Good luck in your search,
