what's the difference between indesign and photoshop in the field?

Photoshop is not a Full Layout program & this is not a Offset midia Indesign is Full Layout program

InDesign can be used to create a research, newspapers & multiply pages mixing text with photos (Like PowerPoint) and if you scale or stretch the photo, it will maintain its original resolution so you can increase its size after decreasing it , but Photoshop you can only create a single file like a poster or adding effects to a photo (more artistic) and if you decrease a photo size, you can't increase it again, you should remove of your PSD file, then use the original file.

Indesign is more like quarkxpress ...
an advanced word editor with graphic designing options ...
on other words ....
Indesign in Adobe is more like MS-Word in MS-Office ..
for more info about Differences Between Photoshop, Illustrator and InDesign ...
Please see this helpful links : http://ezinearticles.com/?Differences-Between-Photoshop,-Illustrator-and-InDesign&id=1791948 http://www.davidjrush.com/blog/2011/01/photoshop-illustrator-and-indesign-whats-the-diff/ http://www.becagency.com/illustrator-vs-photshop-vs-indesign-whats-the-difference/

Indesign is a page layout designer primarly aimed at creating publications ranging from basic business cards upto full blown magazines.
Indesign lets you create postscript files to process into high quality PDFs for print or for web, and even integrate flash files/movies into the web versions of the PDF.
In the field, it's great for creating multipage publications in various page sizes - where one can combine vector based objects, vector text, and rasterized images into limitless ideas.
In short, Indesign is your page editor software.
Photoshop is an all-rounder design app, primarly aimed at editing images using large palette of tools and filters.
From adjusting brightness levels to creating new art with touch-sensitive brushes, photoshop lets you manipulate images at will.
Combine it with text, shapes, adjustment layers and a host more manipulation items, you can create and save your artworks into various file formats ranging from web friendly images to high resolution CYMK images for print.
Basically, Photoshop is an image editor, with newer versions allowing you to even edit 3D objects and smart objects which retain their original pixels information even after editing.