PCs vs. Foils
A PC is a playable character that someone apps with the intention of keeping said character around indefinitely. These are the characters you can play every day. They go to class, they work, they go to stores and coffee shops and to the park. They have lives that make it easy to get RP with them in virtually any scenario.
A foil is a character that is apped as part of a story or is used to further RP in an almost NPC-like manner. This character is either temporary or is one of those people you just can't imagine running into at the mall. These characters will fulfill their purpose and then go away. It is possible for a player who is not staff to have a foil, provided they have apped the story or situation that character is a part of.
FC vs. OC
Here at City of Lights, we accept both OCs and FCs. An FC is a Feature Character, one who is canon for the comics themselves. An OC is an Original Character, one who was birthed from the mind of a player and exists only in fan-run games and stories such as this.
Mutates vs. Mutants
A Mutant is a person who's DNA holds the X-Gene. This X-Gene is the source and origin of their powers. If this gene were neutralized, they would be without powers. This gene is readable by technology, such as is found within Sentinels. It is present at birth, but only activates during the puberty years (possibly sooner depending on stress factors). It is impossible to predict what powers will manifest when this gene kicks in.
A Mutate is a person who was normal, DNA and all, until Something Happened. This term is sometimes used interchangeably with Altered Human. Maybe they were dropped in a vat of radioactive waste. Maybe they were bonded with a cybernetic arm. Maybe they were touched by some sort of supernatural force. Whatever the reason, it is anything but the X-Gene. Keep in mind when apping a Mutate/Altered Human, there are a lot of options, and the catalyst will need to be explained.