Creating record types on Account called Partner and Customer is the recommended way to display only the information applicable to each group. Record types allow different page layouts, picklist values, and business processes to be assigned to different users based on their profile. For example, the Partner record type could have a page layout that includes fields specific to partners, such as Partner Type, Partner Level, and Partner Status. The Customer record type could have a different page layout that excludes those fields. Using Account for customers and creating a custom object for partners would not be advisable, because it would create data silos and make reporting and sharing more difficult. Creating custom objects called Partner and Customer would not make sense, because they are both types of accounts and should use the standard Account object.