Here are some facts.
Biden & Pence alerted NARA that they had government documents (confidential/secret/top secret/etc) at home. They turned them over to NARA. The FBI conducted an investigation. Both were cleared.
Trump didn't tell anyone he had the documents, but kept them on a stage or in a bathroom or whereever. NARA told him "we know you have some documents. Give them back."
He refused.
They threatened him with a subpoena if he didn't. He turned over some documents. Then had his lawyers sign some paper that said they searched the whole place themselves, and didn't find anymore.
The FBI raided and found boxes and boxes full of government documents (confidential/secret/top secret/etc) in Mara Lago.
Trump was indicted for attempting to hide government documents.
Do you see the difference between how they were treated? Do you understand why?