According to (link) “Lead Conversion is the process of converting a lead into an account, contact, and/or opportunity”. From both my professional experience and my studies in marketing, sales and customer service, lead conversion is where qualified leads (i.e., sales ready leads)  are converted into sales. If you are looking at a comprehension lead management system, then lead conversion would follow lead generation in the process.
Lead qualification is the process of quickly turning your leads into “sales ready” or “fully qualified” leads. I believe that this needs to be contrasted with the lead generation process, which seeks to quickly convert inquiries into leads. That is, find out who can and who can’t use your product. For example, you only sell diesel fuel in your service station. Now, a car pulls up looking for non-diesel fuel. Is this a person that
Demand Generation is said to be the focus of targeted marketing programs to build and drive awareness; generate interest (resulting in inquiries, which is the beginning stages of a lead); in a company’s products (goods and services).
It is said that sales is the life line of any business; without sales, there would be no business.  If that is true, then leads must be the heart of the sales process; because without leads, there can be no sale. In many circles, leads are seen as the driver of  the sales process.
According to link, ” Lead nurturing is the process of building a relationship with a prospect by initiating dialog that helps to move [less than fully] qualified prospects that are not yet sales-ready, regardless of budget, authority or timing through the sales pipeline”.
According to an article, I came across the other day,  (link), one of the best ways of making this determination is to score the opportunity.  That is, you give the opportunity points for how qualified it is based on the criteria for qualification. For example: 1. If the opportunity has a decision maker, you score the lead a 5; if it does not have a decision maker, you score it a zero; 2. If the
What is a sales ready lead? It is a lead that fits all the criteria for being qualified enough to warrant sales attention. There is an acknowledged need, want or desire The person has the power to say yes or no to your offer (decision maker) The person has the means (the money) to purchase your offer The person is wiling to listen to what you have to say about your offer During the lead