All option zooms to display all visible objects and visual aids.

Extents option zooms to display the maximum extents of all objects. The extents of each object in the model are calculated and used to determine how the model should fill the window.

There are times when doubling click with the mouse middle button and the drawing will align center, but with ALL in zoom command, the drawing becomes invisible.

That’s because Extents will display all visible objects while All will take LIMITS and visible objects into consideration at the same time.

The following is an example:

1. Create a new drawing and since the template file already has drawing limit, we don’t need to set it again.
2. Draw a circle far from the origin, shown as below,

3. Double-click the mouse middle button, and the circle will be fully displayed, shown as below,

4. Enter ZOOM command, and select All, the position of the circle changes, shown as below,

As we can see from above, All in Zoom command is to display both the drawing and the drawing limit, so if the drawing is big enough to contain the drawing limit, then selecting All in Zoom command will have the same effect as using Extents in Zoom command. But if the drawing limit is too big and is well beyond the drawing, then their effect would be very different.