Once upon a time, programs were compiled and scripts were interpreted. Hence the 2 names. But today, this is 'a distinction without a difference'. My attitude is that the 2 words, program and script, are interchangable. Program and process, however, are different.
Program means a program on disk.
Process means a program which has been loaded by the operating system into memory, and it being executed. This means a single program on disk can be loaded and run several times simultaneously, in which case it is 1 program and several processes. Web servers have names like Apache, Zeus, MS IIS and TinyHTTPd. The feeble security of IIS makes it unusable in a commercial environment. My examples will use Apache as the web server.