canvas different on android emulator compared to phone

Question

Should there be any difference between a canvas on the emulator and a canvas on a real device (HTC Incredible)?

On my canvas for the emulator I have this:

canvas.drawRect(x*cell_size + 1, y*cell_size + 1, x*cell_size+cell_size, y*cell_size+cell_size, pWalls);

(this is a grid type game) and it works and looks fine but on my real device, I have to subtract 1 from the bottom/right params to get it not to overlap the grid lines around it. Why is there this difference?

Also on my real device, it doesn't show the line at (0,0) to (width,0) and I don't understand why not either.

This is all in a custom view.