Microsoft Office 4.2 completes the transition started with Office 4.0 (they skipped 4.1). All of the Office components now support OLE2 and have consistent user interfaces between platforms and applications.
It includes Word 6.0, Excel 5.0, and PowerPoint 4.0. It does NOT include Microsoft Access.
It was released for Windows 3.1, the Apple Macintosh, and i386/Alpha Windows NT. (In the NT package, PowerPoint is still 16-bit)
Later 4.2 releases were rebadged as "Microsoft Office 4.2 Standard" and sold along side "Microsoft Office 4.3 Professional".. The main difference was the addition of Microsoft Access. There was never a "Professional" Office 4.2. Likely the reason for this was it let them keep the Macintosh version the same, as Microsoft Access was never ported to the Mac.