At least in Forex you can get the hell out of a trade in a split second (if you're with a non-deal desk broker). I've been in penny plays where they've been running or crashing but the volume isn't there and I could not even get out for 30 minutes!
The penny stock mentality may be in Forex - but it only represents .001% of the actual money changing hands. It has no influence, no one can manipulate this market. You can post on every Forex board on Earth that a nuclear bo mb went off in London and the GBP won't be affected (unless it was real of course)
In penny stocks one idiot starts a rumor and the shit hits the fan! In Forex it takes a global event, and the banks have to decide to make a move. You, I and thousands of retail Forex traders are NOTHING. That's the difference.