Typically (as I am not intimately familiar with Iowa's real estate laws), an abstract of title is a document that is produced that contains the history of a parcel of real estate from the beginning of statehood to the current owner. Each deed, mortgage, lease, or document that affects the real estate is listed in summary fashion in the abstract. The history is "abstracted", pulled out as a summary, An abstractor searches the court and county records to determine which are the relevant documents. The abstract is for the buyer's benefit and is typically reviewed by one's attorney prior to the closing to see if there are any concerns that would cause raised eyebrows.
A warranty deed conveys property with the following covenants or warranties: covenant of seisin (possession), covenant against encumbrances, covenant of quiet enjoyment and covenant of further assurance. This deed is to assure a new owner that the past will not be an issue, that the title is clear, issues are resolved or at least were disclosed and incorporated into the specifics of the warranty deed...but first and foremost, that ownership has legally changed.