When you move or copy a page or spread from one document to another, all of the items on the page or spread, including graphics, links, and text, are copied to the new document. Threaded text frames are also included, but text that is threaded to pages outside the spread does not transfer. If the page or spread you are copying contains styles, layers, or masters with the same names as their counterparts in the destination document, the destination document’s settings are applied to the page or spread.
If you copy a page from a document that has a different size than the document you are copying to, it will be resized to the dimensions of the destination.