Terrorists or Guerillas?

I recall a definition of "terrorism" from my childhood in the 1970s, one that seems to have gone down the memory hole: "Guerillas attack military targets. Terrorists attack civilians."

The 1970s was a time when terrorism was much in the news. You had the Symbionese Liberation Army, the Baader-Meinhof Gang, the Red Brigades, the Weather Underground. The IRA and PLO were also much active. So terrorism was much talked about, even in the Weekly Reader, the paper of record for the grammar school set. :-)

I don't recall the above as a controversial distinction between guerillas and terrorists, though I never hear it used any more. Instead, the definition of "terrorist" seems to have broadened. But does anyone else remember this 1970s distinction?