And if you'd like a correct answer, go with my one.
NOR: Permanent memory. Will stay there until either you reflash it, or the NOR itself dies, which in practical terms, is probably not worth worrying about. As such, switch the cart around and use it in any combination of DS/Lite and GBA/SP/Micro, or Game Boy Player. Essentially, it will behave like a genuine GBA cart. Slow loading. Not battery backed.
PSRAM: Temporary memory. Will stay there until you shut off the DS. Rapid loading, but you can only use it until you shut off the DS; no moving it to other systems to play there. Not battery backed.
SRAM: Where saves are stored. Backed up by battery. Will stay there until a) the battery dies and b) the power is shut off. Obviously it's fairly useless once the battery is dead, since there's no practical way to back up your save any more.