Some House Democrats are convinced that they'd have better luck getting testimony and documents if they launch an impeachment inquiry against President Trump — which is why they've been pushing House Speaker Nancy Pelosi so hard.

Reality check: It's not like the Trump administration would suddenly drop its fight against Congress and dump a bunch of documents in Pelosi's arms. The big difference between an impeachment inquiry and a regular investigation, legal experts say, is that Congress might have a stronger hand in the courts to get some of the information it wants.

"If you have an impeachment proceeding, Congress is at the zenith of its power," said Michael Conway, a former counsel to the House Judiciary Committee during Watergate.

The two big differences:

1) Grand jury material: The courts would be more likely to rule that Congress' need to see grand jury materials — the kind of references that were redacted in the Mueller report — overrides the federal rule that requires those materials to be kept secret.

That's what happened during Watergate, Conway said, in a critical ruling by a federal judge that allowed the Judiciary Committee to see a grand jury report. (Conway wrote more about that ruling and others here.)

2) Legislative purpose: It would be harder for the Trump administration to win a court fight by arguing that Congress doesn't have a "legitimate legislative purpose," the reason Treasury Secretary Steven Mnuchin cited in his decision not to release Trump's tax returns to the House Ways and Means Committee.

No one questions the congressional power to impeach, so launching an impeachment inquiry "removes whatever doubt a court might otherwise have about the existence of a legitimate Article I purpose for demanding information of limited facial relevance to possible congressional legislation," Harvard law professor Laurence Tribe wrote in an email.

The bottom line: None of this affects the political decision of whether it's wise for House Democrats to move ahead. Pelosi says it isn't, and so far most of the Democratic committee chairs are siding with her. But it's not clear how long they'll be able to resist the pressure.

Go deeper: Which House Democrats are calling for Trump's impeachment