Difference in targeting requirements between Scrying and Sending

Question

Sending says (emphasis mine):

You send a short message of twenty-five words or less to a creature with which you are familiar. The creature hears the Message in its mind, recognizes you as the sender if it knows you.

Scrying says (also emphasis mine):

You can see and hear a particular creature you choose that is on the same plane of existence as you.

My question is, is there a difference between "a creature you choose" and "a creature with which you are familiar"? How familiar is familiar? It doesn't seem to require mutual familiarity, seeing how Sending implies the recipient may not know the sender.

So, for both spells, I'd ask:

• Can you target a creature you have met once but never spoken to?
• Can you target a creature you have never met, but gotten a detailed description of?
• Can you target a creature you have never met, and you only know their name?
• Can you target a creature which you can only describe in an abstract fashion (e.g. "the person who ate my pie, whoever that may be")?

I understand that this might be seen as two (or multiple) questions in one, but in my mind it's all under the umbrella of the question: How does the requirement to be "familiar" affect targeting?

My personal ruling so far was to answer the questions above with Yes/Yes/Yes/No for Scrying and Yes/Yes/No/No for Sending.

Answer 1

For Sending you have to know the target well firsthand, so a detailed description wouldn't work. For more information see What does "familiar" mean in the Sending spell?

For Scrying there are different DCs depending on how well you know the target:

Knowledge	Save Modifier
Secondhand (you have heard of the target)	+5
Firsthand (you have met the target)	0
Familiar (you know the target well)	-5

So you can use a detailed description, but with +5 modifier to the target's saving throw.

For things like "the person who ate my pie" ask your DM. I personally would allow this, if this is good for the story, but this is probably against the spirit of the spell.

To my understanding, Scrying always finds a single particular creature if you can point to this creature somehow. So you probably can Scry on the king Gareth just by knowing his name, because he is the one and only king of Damara.

There are also different sorts of connection to the target:

Connection	Save Modifier
Likeness or picture	-2
Possession or garment	-4
Body part, lock of hair, bit of nail, or the like	-10

So if the unlucky pie-eater left a hair, you can Scry on them.

The Standard Caveat: D&D 5th edition empowers the DM in ways that 3rd, 3.5, and 4th did not. While rule zero has always applied, 5th edition chooses not to explicitly codify many things. If your DM says you can't, you can't.