Fess up and Give up

Fess up verb - To accept the truth or existence of (something) usually reluctantly.

Give up and fess up are semantically related In some cases you can use "Give up" instead a verb "Fess up".

Give up verb - To give (something) over to the control or possession of another usually under duress.

Fess up and give up are semantically related in acknowledge topic. Sometimes you can use "Fess up" instead a verb "Give up".