A program for determining luck/morality in Heroes 3!

What is the difference between the first and the second?

Most of the descriptions and text found in the game are stored in resource files (names of monsters, cities, heroes, dialogues, biographies, etc.). This is done to facilitate localization into other languages; you simply need to translate the resource files without touching the executable.
You can install the complete collection and update the resource files to the original English versions.
Alternatively, you can install the English version of the game.
Some believe that the executable itself is English, and the executable from the complete collection may differ significantly.