Warren, for the general public, "smoking" entails inhaling smoke, typically from cigarettes. That's what people (including doctors) are generally after when they ask "Are you a smoker?". Enjoying a pipe is not the same thing, although that's not to say it's not still a risky behaviour.
If you don't believe me, look up the definition of smoking, and you'll find it invariably involves inhalation of smoke.
From Merriam Webster: to suck the smoke from a cigarette, cigar, pipe, etc., into your mouth and lungs and then exhale it
From The Free Dictionary: Smoking is the inhalation of the smoke of burning tobacco encased in cigarettes, pipes, and cigars.
From Wikipedia: Tobacco smoking is the practice of burning tobacco and inhaling the smoke
From Medicinenet: Tobacco smoking: The direct inhalation of tobacco smoke
From the Oxford Dictionary: The action or habit of inhaling and exhaling the smoke of tobacco or a drug.
It's not a distinction without a difference; it's a big difference.
As for frequency, there's also a big difference between two bowls a week, and ten bowls a day.