GemStone/S 64 Bit v3.5 is a major release, including support for X509-Secured GemStone along with many optimizations and improvements. GemBuilder for Smalltalk v8.4 and 5.4.5 add support for GS/64 v3.5 and the recent client Smalltalk versions, as well as other enhancements and bug fixes.
For more details, see the individual product pages, GemStone/S 64 Bit v3.5, GemBuilder for Smalltalk/VW v8.4, and GemBuilder for Smalltalk/VA v5.4.5.