I thought baking soda and washing soda were the same thing. And while they kinda are, they kinda aren't. Remember acids and bases from chemistry class? Well, both soda varieties are bases, but the washing soda is more basic than baking soda. So, don't mix them up if you are cooking!
From everything I have read you can pretty much use the baking soda in your laundry and for cleaning around the house...it will even put out a small fire! And, since you would also use it for cooking, it seems the more versatile or economical choice. The washing soda comes into play for the tougher jobs. So, where you would use baking soda for regular everyday loads of laundry...washing soda might be needed for a holiday tablecloth with major stains...if the baking soda isn't working.
Keep in mind, like acids, bases can be harmful! You need to wear glaves and such if you use washing soda.
Bottom line...I am going to use baking soda for my laundry. I will let you know how it comes out.