The distinction is one of motives and to whom the information is directed.
Broadly, a whistle blower reports apparent or suspected wrong doing in an approved manner to an agency of government, usually for disinterested reasons, while a leaker provides information to the news media or someone else unapproved for the information in order to gain an advantage or promote a cause of one sort or another.
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Thank you for your reasoned response. What you say makes sense. Guess I’m just too quick to draw conclusions about leakers/whistle blowers. But going to the right person w/ information makes sense. I’m not sure in this case why Cantor needed to know about an affair...but then I’m not sure we know everything there is to know about this incident...yet.
As to intelligence agencies especially, this is thought essential in order to remedy and prevent cover ups of abuses and lapses in mission. As for going to Cantor, the federal source probably knew that standard practice had been violated, not just as to the affair, but in the handling of it by the FBI and the Obama administration, including that Congressional leaders were not promptly informed.
My surmise is that the source to Cantor is a mid-ranking federal employee in the FBI or CIA who was alarmed at what was going on. Now though leaks are pouring out to the news media as the security agencies and senior officials scramble to protect themselves.