The discovery of documents from the Biden-Obama administration in at least two locations linked to Joe Biden has been greeted with dismay by Democrats and glee by Republicans, given the extensive legal troubles that Donald Trump faces for taking classified papers to his Florida resort.

Republicans believe the incident shows that Biden has committed the same transgression as the former president, and argue that the FBI raid on Mar-a-Lago and subsequent investigation were politically motivated point-scoring.

But Democrats insist the two incidents are different legally, while acknowledging that they present a political problem for Biden that allows Republicans to go on the offensive.

So what is the real situation? Here are the key points to know:

What actually has happened?

The FBI search at Mar-a-Lago last summer discovered more than 11,000 documents and photos from the Trump administration. They reportedly included highly classified intelligence material as well as more mundane papers. Subsequently more documents were also found.

With Biden, the papers are much smaller in number and hail from his time as vice-president to Barack Obama. The first batch was found at a Washington thinktank linked to Biden, and more documents, including some marked classified, were found by lawyers in a garage and storage room during a search of Biden’s home in Wilmington, Delaware.

Legally, how serious is this for Trump and Biden?

Both situations are being investigated by the US Department of Justice, which will look into the behavior and possible motivations for taking the documents.

Trump appears to have willfully obstructed efforts to recover them, leading to the FBI raid, and the decision by the attorney general, Merrick Garland, to launch a criminal inquiry and appoint a special counsel to weigh charges on the issue as part of a broader brief looking at investigations into Trump.

With Biden, his team said they cooperated fully and immediately returned the documents to the National Archives as soon as they were discovered. Garland has asked John Lausch, a Trump appointee as US attorney for the northern district of Illinois, to conduct a review, but has initially resisted Republican calls for a criminal investigation or special counsel.

What’s in the documents?

In neither case is that entirely clear, although the Trump documents are reported to have included an unidentified foreign power’s nuclear secrets and other military capabilities.

The Biden documents also reportedly contained classified papers commingled with non-classified materials, with the subjects and content yet unknown.

Notably, however, the Trump papers included some dated after his presidency, suggesting he had them while no longer authorized. All of Biden’s seem to be dated while he was in office as vice-president.

What’s the political fallout?

The Mar-a-Lago raid had mixed impact for Trump. Many Republicans despaired at having to defend the former president, while others backed his claims that he was being unfairly targeted.

The Trump team will attempt to exploit Biden’s misfortunes as he pursues his 2024 run to recapture the presidency, while the new Republican majority in the House can, if it wishes, launch its own investigation into the Biden documents.

For Democrats, the discovery of the documents is an unexpected and unwanted political headache. It dilutes their outrage at Trump’s possession of classified papers and hands Republicans an easy talking point on what had previously been a thorny issue.

What are the Trump and Biden camps saying?

The White House issued a statement on Thursday from Richard Sauber, special counsel to the president, conceding “a small number” of documents with classified markings were found among personal and political papers at Biden’s Wilmington home, but didn’t say when. It stressed the president’s lawyers were “fully cooperating with the National Archives and Department of Justice”.

Trump, in a predictable response on his Truth Social network, demanded to know when the FBI would “raid the many homes of Joe Biden, perhaps even the White House”.