You don't have to link modules. Make a program as big as you need! You can use CHAIN or RUN if you want.
The IDE is similar and it does nothing but compile BAS files into EXE files. It doesn't have an interpreter, but you can use QB for that.
It also allows custom sized windows and 256 or 32 bit colors. QB64 has over 100 new keywords. You can put photos or pictures directly into programs without all of the hassles of Qbasic. It can play WAV files to MP3. It also can use DLL libraries.
QB64 goes way beyond anything you can do in PDS!