That would be Project Builder and Interface Builder. Project Builder was kind of a graphical make tool and Interface Builder was the real star of the show, it was the graphical user interface builder. And there was Edit for source code editing.

There were sold as separate product, NeXTStep Developer that had all the development tools, but if you bought the education version of NeXTstep the developer tools came bundled.

The Developer CD for the 3.3 release is in the CD-ROM drawer, you should be able to mount it and install IB and PB.

Besides the sibling comment, that was kind of Smalltalk like, in the sense how code navigation and code editing was implemented.

You can also get a glimpse of it on the famous NeXT vs Sun commercial.

https://www.youtube.com/watch?v=UGhfB-NICzg