ExileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) target instant or sorcery card from your graveyard and target instant or sorcery card from an opponent's graveyard. Copy those cards.
CastTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) the copies if able without paying their mana costs.
ExileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) Spelltwine.