Often, organizations track Lead data and Opportunity data in separate locations and teams. Days to Convert will be a metric tracked on Leads, and should be determined by creation date to the date they converted into a Contact. Days to Close Deal will be a metric tracked on Opportunities, and should be determined by opportunity creation date to the date that the Opportunity Stage turned into Closed Won. Usually, this can be found in an Opportunity report filtered to "Closed Won" only with the "Last Stage Change Date" or "Close Date" indicating the final date.