Indeed they are not the same thing. A platform pedal is technically a type of pedal designed specifically for use with toe clips. They are one-sided use only, with a platform on the toe clip side for the rider's shoe. Most high-performance pedals of the toe clip era were platform pedals. Nowadays, lots of people use the term to refer inaccurately to plain pedals, which are your basic pedals without toe clips, to the point that platform and plain pedals are now pretty much synonyms. In other words, they weren't the same thing, but now they are, so I guess you can keep calling them platform pedals if you want.

Um, anyway, I used toe clips while I commuted to my part-time job, and when cruising around campus. Now that I don't have that job and don't need to go more than a mile or so beyond my campus on a regular basis except by bus, my touring bike is at my parents's house, and I'm cruising around campus on my beater, with plain rattrap pedals. I love toe clips, and will soon be making the transition to clipless on my nice bike (thanks, max-a-mill!), but I actually prefer the plain pedals on campus, where I don't need to worry about getting in and out of clips every two minutes or so.