For me, the main difference is that a script is interpreted, while a program is executed (i.e. the source is first compiled, and the result of that compilation is expected).
Wikipedia seems to agree with me on this :
Script :
"Scripts" are distinct from the core code of the application, which is usually written in a different language, and are often created or at least modified by the end-user.
Scripts are often interpreted from source code or bytecode, whereas the applications they control are traditionally compiled to native machine code.
Program :
The program has an executable form that the computer can use directly to execute the instructions.
The same program in its human-readable source code form, from which executable programs are derived (e.g., compiled)