There are dozens of changes (actually a lot more...), but to list a few of the biggies...
Starting with NX 5.0 we changed the style and behavior of most of the dialogs in NX. The good news is that they are now much more consistent when you go from one function to another or use common sub-functions.
Also starting in NX 5.0 we replaced the old Hole feature command with a totally new one covering virtually all of the ER's which people had submitted over the years.
Also with NX 5.0 we introduced Assembly Constraints as an eventual replacement for Mating Conditions (starting with NX 7.5, Mating Conditions can no be used but legacy files containing Mating Conditions will continue to be supported and they will update as expected as parts change).
Also Edit -> Transform has been obsoleted and replaced with a new Move Object command.
There have been many enhancements to Sketching.
And last but not least, an entire new concept of Synchronous Modeling has been introduced which replaced the old 'Direct Modeling' routines.
All in all, there's a lot that you will need to catch-up in, but if you try and get ahold of the various 'What's New' documents from NX 5.0 thru NX 7.5 that will surely help.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
To an Engineer, the glass is twice as big as it needs to be.