Thanks for your query.
Well, Aspose.Cells follows MS Excel standards and specifications when rendering to PDF file format. You may surely hide your unwanted worksheets except your desired sheets (i.e., all sheets without chart sheet type) for case1 and render to PDF (e.g out1.pdf) file format. Then you may hide all sheets except chart sheets and render to out2.pdf for case2. But how could you manipulate and render in single PDF file (as per your description), this is not possible (even in MS Excel either) because Aspose.Cells is a spreadsheet management library rather than PDF management component. One way can be you render two PDFs by Aspose.Cells APIs and then use Aspose.PDF to merge both PDFs into single PDF.
But if you want to accomplish the task using only Aspose.Cells APIs, we can devise a workaround, i.e., by using Worksheet.MoveTo() method and using your own code, you may move a worksheet to another location in the same worksheet. So, you got to move certain worksheets at their specified (according to your needs, i.e., first normal worksheets should be in place and then chart sheets should be pasted) indexed position in the workbook, see the document for your reference:
after you have done all the worksheets in place (in the workbook) according to your needs, you may now render to PDF file by Aspose.Cells APIs.
Hope, this helps a bit.