OP,
Whether these pm-series scopes say "Philips" or "Fluke", they were made by the same company in the Netherlands.
Philips N.V. and John Fluke Corp. formed an alliance in the mid-80s to develop and market test equipment, and Fluke finally bought that division from Philips in the early '90s. Both company's logos appeared on the same range of oscilloscopes, made in Eindhoven.
The -B series of scopes was an update in around 1998. Expanded and more flexible memory was standard on the pm3384B, while it was only an option on the pm3394. The 3384B has lower vertical bandwidth, but this was achieved by using different passive components around the LNA, as in so many other instrument series.