Are the descriptions different or is it that the wording is different? The descriptions may have different wording as a result of different surveyors doing the survey on the piece of property.

Further, there could be circumstances that caused the metes and bounds to have changed in a description.

You have to clarify your question a bit - how much time has passed between the documents that you are looking at? Were the surveyors the same for both documents, and etc.

In a general sense though, the wording can be different, and the content could be as well if there is something in the chain that has caused a change in the metes and bounds...

Or you could be looking at someting that was simply given the wrong description - common mistake due to misfiling at either the Recording Office, or even at the Title Company...