Differences between office InterOP and tools

For example, what is the difference and connection between Microsoft. Office. InterOP. Word and Microsoft. Office. Tools. Word?
We said that InterOP is still. the InterOP concept in the general sense of netframework enables the Office COM Object Model.. net, while tools extends the InterOP so that the Office can be used better.
For example, you can directly use bookmark. TEXT = "strings". After the value is assigned, bookmark is still normally surrounded by these strings, instead of bookmark. range. TEXT = "strings", and then re-create a bookmark with the same name to enclose the strings again. Obviously, the operation is much easier. In addition, you can also use new properties that are not directly available in office tools, such as data caching and actions panes.