Spice is primarily an analogue simulator. It can handle audio amplifiers just as well as simulating digital logic circuits. Digital, as the name implies, does

Spice is primarily an analogue simulator. It can handle audio amplifiers just as well as simulating digital logic circuits. Digital, as the name implies, doesn't deal with the analogue at all, it's a graphical logic simulator. Step-based, fixed signal values like 1, 0, not connected, high-impedance. Think visual Verilog, except somewhat limited. There is some support in Digital for defining component behaviour in Verilog or VHDL. Once defined, you will get a graphic symbol you can put in your diagram, and all the wires will behave as specified in the code. It's also possible to translate a schematic in the software to Verilog or VHDL code. Because of that, I do think it would be a good stepping stone to learning more about logic and hardware description languages. I've recommended it before to people who want to learn the basics. But it's still new, has some limits, and I don't think it would scale well to a large project.