Odoo is a suite of open source business apps to cover all your business needs: CRM, eCommerce, accounting, inventory, point of sale, project management, etc. Because of its adaptable architecture and modular structure, SMBs can leverage Odoo to meet specific and unique needs. Odoo's unique value proposition is to be very easy to use and fully integrated.
ERPNext is an open source integrated Enterprise Resource Planning platform aimed at small and medium sized businesses. It assists companies with accounting, human resource management, purchase, sales, inventory, CRM, administration, project and task management, manufacturing etc.