Why are there multiple CSS classes that mean the same thing?

There's the following pairs with the same semantic meaning:

 - `htmlElementName` and `xmlName`
 - `htmlAttributeName` and `xmlAttribute`
 - `comment` and `htmlComment`
 - `string`, `jsonString`, `xmlAttributeValue` and `htmlAttributeValue`
 - `cssPropertyName` and `jsonKey`

Is there a reason these are separated out instead of just using the same class name?