What is the difference between give something to someone and give something away to someone in the sense giving that thing for free or as a present? For example:
I'm going to give the phone to Kate. I don't use it anyway.
I'm going to give the phone away to Kate. I don't use it anyway.
I'm going to give the phone to Kate. I don't use it anyway.
I'm going to give the phone away to Kate. I don't use it anyway.
"give" needs a direct and and indirect object.
I'm going to give to Kate. (incorrect)
I'm going to give the phone. (incorrect)
"give away" only needs a direct object.
I'm going to give the phone away. (correct)
I personally would never use "give away" with an indirect object.
I'm going to give the phone away to Kate. (incorrect in my opinion)
Note that if you give something away, you usually have not decided to whom you will give it.
I would suggest that you give away something that already belongs to you. Give on its own could refer to something you have just bought as a present for someone.
"Give" is much broader in scope. You can give things that you do not own -- a child passing out milk in class is giving the other children milk, but not giving it away -- and give them to be a temporary loan -- one man could give another his car for a trip, to be returned on his return, not giving it away.
To give something away can mean to (usually inadvertently) reveal a secret or clandestine activity, e.g. someone involved in a practical joke, organisation of a surprise party or execution of a heist might accidentally mention it within earshot of victim, birthday boy/girl/person or the police.
So, the meaning can differ. Context will usually distinguish the intended meaning.
In general the meaning is similar although giving away strongly implies as a gift, whereas simply giving could be an obligation, part of a trade or repayment of a debt; a loan (or return of one); handing an item to an intermediary for delivery... and so on.
