Joy
The differences is the potency--the number of dilutions and succussions. 30C is much less potent than 1M. I would be very surprised if you got 1M from a local health food store. 30C is the usual, and occasionally I've seen 200C. Lower potencies can be given more frequently than 1M. I have *never* seen 1M sold to the public at a natural food or natural health store and I question that's what you actually got. I've used 1M treating my animals (goats and horses), but rarely, and have always had to order them online. In addition, I am trained in homeopathy.
I hope Dr.Will responds to this, as I'd like to see his answer.