You know that sandbox games are really not open-word ones... or are you serious?
Sandbox games are games that give you tools and you do whatever you want with the tools (like a kid playing in a real sandbox), sandbox games came from games like the original "Tycoon" and "Theme" games (Zoo Tycoon, Railroad Tycoon, Theme Park, Theme Hospital, etc) that would usually come with a game mode called "Sandbox", where there was no missions or objectives and you could just build whatever you wanted the way you wanted.
Classic RTS games Skirmish mode was also considered a type of Sandbox mode.
Open-world games are games where you can access all or most of the game map from the start or the very early part of the game, and that you're free to come and go as you please.
For example, The Witcher 3 is a open-world (at least I hope so, never played it and don't know much about it's map, but others seem to call it an open-world game) but not a sandbox game, because you can't use the tools to do whatever you want and make the world the way you want, etc. So is Daggerfall and Morrowind.
Minecraft and Terraria are Sandbox games because you can use the tools that the game gives you to do and shape almost everything the way you want.
For example, a good example of a sandbox game that is not an open-world is Kerbals Space Program. You can use the tools to construct whatever you want but you can't go anywhere besides the moon and stuff, it doesn't have an open-world at all.
Fallout New Vegas, or actually even all the old Fallout games are open-world but not sandbox at all for example.
These days games tend to try and be both genres, open-world and sandbox, but those are two different genres, like RTS and RPG (as some examples of games that uses both RPG and RTS we have the Warlords Battlecry games or the Spellforce games). We can have games that are both but the genres are different.
Am I the only one that still can differentiate the genres today? Have the game industry forgot all what game genres are?