Thanks for coming back.
Yes, Aspose and GroupDocs APIs are targeted for different use cases. Each of the Aspose APIs targets to a specific file format and provides all the features and operations related to that file format i-e Aspose.Pdf deals with the PDF documents and, similarly, Aspose.Words provides Word document processing features and so on. On the other hand, each API at GroupDocs provides a package of some specific features that are related to a range of the document formats i-e GroupDocs.Viewer provides rendering of over 50 document formats
. Furthermore, at GroupDocs the required features which are available in multiple Aspose APIs are put together and wrapped up into a single API to fulfill a specific purpose.
In your case, as you said, you are going to deal with MS Office file formats that may include Word documents, PowerPoint Presentations, Excel sheets etc. If you go with the Aspose APIs, you will have to use a separate API for each file format i-e Aspose.Words for Word documents, Aspose.Cells for Excel sheets and so on. However, using GroupDocs.Viewer, for example, you can render all the Office file formats using the single API.
In case of any confusion, please feel free to let us know.