No.

The **viewport** is a rectangular region on the **backbuffer** that determines the area in which the rasteriser draws pixels. A viewport (X,Y) of (0, 0) is always the top-left corner of the backbuffer (in XNA). You can freely move and resize it *within* the backbuffer.

The **backbuffer** is the underlying surface that the GPU is drawing to. To resize it you have to reset the graphics device. It doesn't have a position of its own - it is drawn on whatever window it is attached to, using that window's position (in this case, a panel counts as a window).

When rendering, the rasteriser takes inputs in **projection space**, converting vertex positions to pixel positions within the **viewport**. The position (-1, -1) in projection space is in the bottom-left of the viewport, and (1, 1) is in the top-right. To transform the 3D vertices in your world into projection space, you use a projection matrix.

(`SpriteBatch`'s default projection matrix lets it take input coordinates in client space within the viewport.)

Here are some references about <a href="https://gamedev.stackexchange.com/a/8694/288">the various things that determine display size</a> and about <a href="http://stackoverflow.com/a/3539665/165500">projection space</a>.