If they're both in use, then they're both correct - and you interchange them for stylistic purposes.

A passage by David Crystal from 'Words Words Words'; "The choice between alternative noun plurals is a fairly easy one. Is it formulas or formulae? Cactuses or cacti? Referendums or referenda? The regular -s ending is usually the more informal and colloquial. The classical ending is the more technical, learned, or formal. If I am a plant amateur, I will probably say cactuses when I see more than one of them. But if I am a cactus aficionado, I will almost certainly say cacti."