On Linux, it is common to install Ghostscript and make its fonts available to the system. Doing this has the result of mapping standard Postscript typefaces (e.g. "Helvetica", "Times", "Palatino", "ITC Bookman", "ITC Avant Garde Gothic") to their Ghostscript implementations (respectively "Nimbus Sans L", "Nimbus Roman No9 L", "URW Palladio L", "URW Bookman L", "URW Gothic L").
This has the effect of causing Firefox to render "Times" as "Nimbus Roman No9 L", while still mapping "Times New Roman" to "Liberation Sans"; and likewise for "Arial" / "Liberation Sans" and "Helvetica" / "Nimbus Sans L"
On Linux, it is common to install Ghostscript and make its fonts available to the system. Doing this has the result of mapping standard Postscript typefaces (e.g. "Helvetica", "Times", "Palatino", "ITC Bookman", "ITC Avant Garde Gothic") to their Ghostscript implementations (respectively "Nimbus Sans L", "Nimbus Roman No9 L", "URW Palladio L", "URW Bookman L", "URW Gothic L").
This has the effect of causing Firefox to render "Times" as "Nimbus Roman No9 L", while still mapping "Times New Roman" to "Liberation Sans"; and likewise for "Arial" / "Liberation Sans" and "Helvetica" / "Nimbus Sans L"