What Separates CRM from Sales Lead Management Software?

There has been a steady drum-beat of an emerging category of software to manage sales leads. The category is Sales Lead Management. While Sales Lead Management is a big tent that encompasses many different disciplines and tools, if you search for the category of sales lead management software there are new entrants that say they aren’t CRM. Or are they? Are these “entrants” just CRM companies that separate themselves from a crowded field?