Cruisers and battlecruisers in Star Trek

What is the difference between a cruiser and a battlecruiser in Star Trek, including for the Klingons?

A Starfleet battlecruiser is described as a cruiser that trades scientific facilities for weapons. Klingon usage instead emphasizes a large, fast warship.

The proposed Starfleet distinction is to turn a cruiser into a battlecruiser by removing scientific equipment and adding weapons and associated systems. That interpretation also explains the objection to calling the Galaxy class a battleship. Klingon terminology is treated differently: a battlecruiser is a large, fast fighting ship, while the battleship category can include something larger and slower. The example shows why one setting's classification cannot simply be applied to every navy within it.