is partner vs is customer

I think partners and customers are definitely not mutally exclusive, but it might depend on your business type. 

You can create a checkbox that marks them either as a customer or consumer based on a trigger campaign when they come into your system. (Trigger is: new lead is created, if ____ then change data value in _____ field). The only nuance is if the criteria that you determine them upon isn't available. To be safe, you can also create a campaign where if the lead is created and ends up being blank, you send them an email to collect that data.

However, if you're not supposed to be marketing to either, then you should consider utilizing workspaces. Workspaces allow you to partition your leads and organize them so they will receive the appropriate data. It is the easiest way to market to both customers and consumers in a single instance without having any overlap or hesitations.
 

You should have a field on a record to identify it as such. Some firms have a Record Type ID indicating this, others just a field.

Sorry - I asked the question incorrectly. My question is - what is the purpose of the "Is Partner" and "Is Customer" default fields of Marketo?