question about PAC and PCS files

[Innerscope]

These two files are the same, except that PCS is a compressed PAC file.

I need some confirmation.

Is the following true?

PAC files are used in adventure stages (example: SSE)
PCS files are used in battle stages (example: multi-man brawl)

If this isn't true, why do we have both of these? (instead of only 1)

 

[ThunderBird2678]

These two files are the same, except that PCS is a compressed PAC file.

I need some confirmation.

Is the following true?

PAC files are used in adventure stages (example: SSE)
PCS files are used in battle stages (example: multi-man brawl)

If this isn't true, why do we have both of these? (instead of only 1)

I have no idea for the stages, but in characters, PACs are normal character files, and PCSs are used when a character transforms(zelda/sheik, samus/zero suit samus,the pokemon trainer's pokemon, and bowser/giga bowser). I am confused as to why there would be PCSs for other characters.