tirf.007
In word you can, more or less, see the full width of a page and by zooming see the whole Page or you can select whole page via the tool bar/ribbon. But no matter which one you choose you can still work with the page. Selecting portrait or landscape just means you can set your page contents out in a different way.
If you tried to get an Excel to show all of the sheet you would not be able to work with it, it would be too small, you can set areas in your spread sheet to match either portrait or landscape so that your data is laid out as per sheet orientation and if you change the portrait or landscape via the tool bar/ribbon but that is only to change the print orientation, it is easier just to select your data and then choose print selection, preview and adjust print area to suit. There are times that with all the will in the world you will not get all the data you want on to one print sheet without it being unreadable. Plat around with the Page setup section to get the data to print as you need.