CSV is the abbreviation of Comma Separated Values. But in some countries, it is common to use a semicolon as separator, so there are used both Comma separated CSV files and Semicolon separated CSV files. I would say both separators are correct.
Excel can work with both types of files, so there should be no difference when the CSV file is comma or semicolon delimited. You need to choose in Windows regional settings, if comma or semicolon has to be used as delimiter.
To change the settings in Windows 10, you have to:
1. Go to Control Panel
2. In Clock, Language and Region section, click on Change the date, time, or number formats
3. Click on Additional settings button
4. Type or select a comma or semicolon in the List separator box
5. Confirm the change