When an organization sell new stocks to the investing public for the first time this is known as Initial Public Offering (IPO), this is mostly done through an investment bank or finance syndicate of securities dealers.
When an organization offers new stocks to the public, stocks that has not been sold before, this is known as primary issue stock.
In a situation whereby the organization has already raised an IPO and want to raise more funds by offering more shares, these shares will be categorized as Non IPO shares.
Hope this helps.