Generally, an effect that isnt putting cards directly in your hand at activation, will tell you to "pick up" cards and discard at resolution.
Examples:
Painful Choice
Morphing Jar #2
Monster Gate
Cyber Jar
Effects that activate and tell you to "draw" cards, usually leave you with a card(s) in hand.
Examples:
Pot of Greed
Mirage of Nightmare
Morphing Jar
Graceful Charity
Basically, if you are told to "pick up cards", these cards are not considered in hand unless the effect specifically instructs you, or your opponent to select or choose a card to remain in hand and most likely all others will be sent to the Graveyard and are only eligible for effects that send cards "from the deck to the Graveyard".
If you are told to "draw card(s)", that card or cards will remain in hand and if an effect tells you to discard or send a card, it will have been sent from your hand and is eligible for effects that send cards "from hand to the Graveyard".