The answer to that question depends upon which platform/device you're playing the game on and where/when you obtained the demo version.

Since you posted this in the Windows/Mac section, I'll give the answer for the desktop versions of VV4: If you downloaded the current demo version from our site, you will be able to play the entire game, but with a much smaller tribe than is available in the full version.

If you have an older demo version or one downloaded from a different game site, the above answer doesn't apply, since other game sites often carry different/older versions.