24hr market- In stocks everybody is mostly in the same boat, there is an established pattern of volume. You can use that to your advantage by simply trading for an hour during the most active time period. In Forex volume is more erratic and unstable.

no commissions- There actually are commissions, they are called spreads. It is factored into the trades you make. Forex brokers would not be in business if they didn't get commission. Some Forex brokers can even get unscrupulous and charge you higher spreads if they want to.