I did not read the thread, but there is always confusion around ammunition terminology... it is simple and most experienced people know what is what... the problem is, that we also know that if we use the correct terminology many casual enthusiasts and noobs will not understand. Quite simply;
Loaded ammunition is called "cartridges."
This is what you would buy in boxes of 20 at Canadian Tire (for example).
The lead or copper or alloy projectile that exits the barrel on firing is called the "bullet."
The metallic container housing the bullet and powder (propellant) and primer (ignition) is call a "casing", but may also be referred to as "brass" on the basis of it's most common material.
Bullets are not cartridges, and cartridges are not bullets, but many people use the term "bullet" loosely when they are in fact referring to a "cartridge."
Where the words "tip" or "head" are applied, it is usually by someone speaking to a noob and not wanting them to misunderstand what they are referring to, and thinking "cartridge" when they are actually only referring to the "projectile."
Clear as mud.