Any business that buys and sells (trade) or into project / services business can benefit from using an ERP system. Every business performs activities that are common such as employ people, buy products & consumables, keep accounts and collect invoices. Further some might trade in goods and some might manufacture or procure those from a 3rd party. To track all these activities an ERP system can be invaluable as it helps keep the integrity of your business at all times.
A fully function CRM is available in ERPNext and you can manage your leads, opportunities and contacts from here. You can also create quotations and sales order from the CRM module. The CRM module is fully integrated into Sales, Accounting and further downstream into manufacturing and inventory.