Mainly, BlitzPlus has GUI commands to create Windows-style interface for applications. These are not supported by Blitz3D. BlitzPlus also allows you to choose between Windows GDI, DX1 DirectDraw or OpenGL to draw the graphics, while Blitz3D uses DX7 DirectDraw for 2D graphics.
But maybe the commands that B3D has not recognized are commands from DLLs, which you can use in Blitz copying the .decls file that comes with Blitz Dlls in the 'userlibs' folder of Blitz3D.
But maybe the commands that B3D has not recognized are commands from DLLs, which you can use in Blitz copying the .decls file that comes with Blitz Dlls in the 'userlibs' folder of Blitz3D.