Functionality is similar but the underlying codebase is different. IBM Lotus Symphony is based on the StarOffice/OpenOffice codebase. SmartSuite isn't.
"IBM Lotus Symphony is an set of applications comprising:
* IBM Lotus Symphony Documents, a word processor
* IBM Lotus Symphony Spreadsheets, a spreadsheet
* IBM Lotus Symphony Presentations, a presentation program
It supports the OpenDocument format (ODF), as well as Microsoft Office and Lotus SmartSuite formats, and it can export Portable Document Format (PDF) files.
Lotus Symphony is based on Eclipse Rich Client Platform for its shell and OpenOffice.org for the core office suite code. It shares code with the productivity tools built into IBM Lotus Notes version 8."
"Lotus SmartSuite is an office productivity suite that includes Lotus 1-2-3, Lotus Approach, Lotus FastSite, Lotus Freelance Graphics, Lotus Organizer, Lotus SmartCenter, and Lotus Word Pro."
I've downloaded Lotus Symphony - will install it and report back.